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Anticancer, Azonafide‐Inspired Fluorescent Ligands and Their Rhenium(I) Complexes for Cellular Imaging
A Journal of
Accepted Article
Title:Anticancer, azonafide-inspired fluorescent ligands and their
rhenium(I) complexes for cellular imaging
Authors:Simon J. Pope, Emily Langdon-Jones, Ariana Jones, Catrin
Williams, Anthony Hayes, David Lloyd, and Huw Mottram
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To be cited as: Eur. J. Inorg. Chem. 10.1002/ejic.201601271
Link to VoR: http://dx.doi.org/10.1002/ejic.201601271
European Journal of Inorganic Chemistry 10.1002/ejic.201601271
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Anticancer, azonafide-inspired fluorescent ligands and their
rhenium(I) complexes for cellular imaging
Emily E. Langdon-Jones,[a] Ariana B. Jones,[a] Catrin F. Williams,[b,c] Anthony J. Hayes,[c] David Lloyd,[c]
Huw J. Mottram,[d] and Simon J.A. Pope*[a]
Dedication ((optional))
Abstract: Two dipicolyamino-conjugated anthracene-1,9- emission tomography (PET) and single photon emission
dicarboximide fluorophores and their corresponding Re(I) complexes computed tomography (SPECT). Both Tc and Re are obvious
have been synthesized and photophysically examined. All species choices in this respect,[3] hence 99mTc (t = 6.01 h, g = 142.7
1/2
were fluorescent in the visible region ca. 490 nm with lifetimes up to keV) continuing to be routinely used in the clinic, and 186/188Re
16 ns. The anticancer potency of the ligands and complexes was (186Re t = 3.68 d, b = 1.07 MeV, g = 137 keV; 188Re t = 16.98
1/2 1/2
demonstrated across a range of cancer cell lines (LOVO, PC3, A549, h, b = 2.12 MeV, g = 155 keV) being increasingly investigated in
MCF-7). Cell imaging studies using MCF7 cells and radiopharmaceutical therapies.[4] Both PET and SPECT have
Schizosaccharomyces pombe show that these fluorophores show relatively poor imaging resolution and cannot be utilised as
variable intracellular localization patterns that are structure dependent. imaging techniques at the micron-to-nanometer cellular level.[5]
Therefore, to identify any cellular uptake and localisation
phenomena it is essential to tag such ions with fluorescent labels
(in this case ligands) that allow confocal fluorescence microscopy
Introduction
to be used. This is an essential tool in the assessment and
validation [6] of prospective bioimaging or therapeutic agents
based on metal complexes. In particular, the design of
The combination of a fluorophore (i.e. fluorescent ligand) with a theranostic agents [7] should benefit greatly from such as
selected metal ion of bioimaging or therapeutic relevance and approach.
confocal fluorescence microscopy is a powerful approach for
investigating the biological behavior of metal complexes.[1] In this
context, the fluorescent ligand should be compatible with the
H N
2
excitation light sources of the microscope, and can help track the
distribution of the complex in an intracellular environment. Of
course, the ligand can also be designed to be biologically active,
for example through interactions with biological molecules (e.g.
DNA, proteins), and can thus deliver therapeutic activity in its own
O N O O N O
right. The choices of metal ion in such a complex also provides a
rich gamut of design options, particularly if one considers the use
of metallo-radionuclides.[2] Such ions can be used in positron
N N
[a] Dr. E.E. Langdon-Jones, Ms A.B. Jones, Dr. S.J.A. Pope Amonafide Azonafide
School of Chemistry
Cardiff University
Cardiff, UK CF10 3AT
Scheme 1. The molecular structures of amonafide and azonafide.
E-mail:
[b] Dr. C.F. Williams
School of Engineering
Cardiff University Early examples of this approach were described by Alberto and
Cardiff, UK CF24 3AA
co-workers and involved the development of fac-tricarbonyl
[c] Dr. C.F. Williams, D. A.J. Hayes, Prof. D. Lloyd 99mTc(I) complexes. In these cases, either pyrene [8] or acridine
School of Biosciences orange [9] based fluorophores were conjugated to the complex
Cardiff University
and allowed the cell uptake and nuclear targeting behavior of the
Cardiff, UK CF10 3AT
complexes to be established. More recently we have explored
[d] Mr. H Mottram the use of substituted naphthalimide fluorophores as component
School of Pharmacy
of cell imaging agents. Ligands based upon 4-amino-1,8-
Cardiff University
Cardiff, UK CF10 3NB naphthalimide can be functionalised to allow conjugation with
either Re(I) (via a dipicolyl amine unit) [10] or Au(I) (via a terminal
Supporting information for this article is given via a link at the end of the
alkyne).[11] In all of these cases the specific nature of
document.((Please delete this text if not appropriate))
functionalization at the naphthalimide core promotes very
distinct intracellular localisation patterns.[11] Interest in the
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European Journal of Inorganic Chemistry 10.1002/ejic.201601271
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biological application and cell imaging capability of substituted
i) ii)
naphthalimide fluorophores has grown significantly over the last
five years. Recent examples include antitumor [12] and antiviral
O O O O O
[13] derivatives, biocompatible fluorescent micelles for imaging iii) iv)
[14], live cell imaging of metal ions,[15] mitochondrial localising NH2
two-photon absorption probes,[16] and imaging in live
N
N
zebrafish.[17] v) N
O N O O N O
v) NH2
Our initial interest in naphthalimide derivatives [10,11] emanated O N O N2
from the biological properties of the structurally related species NH2
N1 O N O
amonafide (Scheme 1), an anticancer drug [1,18] currently in
N N
phase III clinical trials.[19] However, the anthracene-1,9- N N
dicarboximide derivative azonafide,[20] which is a prospective L1 L2
N N
anticancer drug, has shown dramatically enhanced anticancer
properties versus amonafide. Functionalised anthracene-1,9- vi) vi)
dicarboximide derivatives were first developed in the 1980s by O
Braña et al where their DNA intercalating properties were N BF4 BF4
investigated.[21] Subsequent work led to the development of O O
azonafide (Scheme 1), and studies have examined the structure- N N N
activity relationships of closely related species.[22] Generally, N Re CO O N Re CO
azonafide derivatives have shown a greater potency when N CO N CO
CO CO
compared to amonafide, where the enhanced DNA binding [23]
fac-[Re(CO)3(L1)]BF4 fac-[Re(CO)3(L2)]BF4
strength is thought to play an important role.[24]
Scheme 2. Synthetic route to the ligands and complexes: i) oxalyl chloride, CS,
2
anhydrous AlCl; ii) NaOH, 30% HO, 1,4-dioxane; iii) 1,6-diaminohexane,
3 2 2
EtOH; iv) 1,2-ethylenediamine, EtOH; v) 2-pyridinecarboxaldehyde, 1,2-
The reactivity and dimerization of anthracene-1,9-dicarboximide dichloroethane; (iv) fac-[Re(CO)(MeCN)]BF, CHCl.
3 3 4 3
derivatives have been reported [25] and anthracene-1,9-
dicarboximide fluorophore can emit in the green part of the visible
spectrum.[25] However it is remarkable that in the course of the For the synthesis (Scheme 2) of the fluorescent probes,
biological studies of these species described earlier the anthracene–1,9–dicarboxylic anhydride (ADCA) was obtained via
literature methods.[28] Treatment of ADCA with either 1,6-
fluorescent properties have not been more widely exploited in a
diaminohexane or 1,2-ethylenediamine in ethanol gave the amine
bioimaging context. In fact, to the best of our knowledge, only one
terminated imide intermediates, N1 and N2. These were then
report (from 1999) exists on the investigation of azonafide
treated with a one–pot reductive amination procedure using 2–
analogues in a cell imaging context.[26] Interestingly, despite the pyridinecarboxaldehyde in the presence of triacetoxyborohydride
demonstrated biological activity of azonafide-type species there in 1,2–dichloroethane. However, somewhat surprisingly, L2 was
are no reports on the incorporation of the fluorescent anthracene- not isolable using this approach. Therefore as an alternative, N,N-
1,9-dicarboximide moiety into ligand architectures for bis(pyridine-2-ylmethyl)ethane-1,2-diamine (obtained from
mono–BOC–protected 1,2–ethylenediamine) was reacted directly
coordination complexes. This naturally raises the opportunity for
with ADCA, giving L2 in high yield. Due to the potential light
the design of dual-functional diagnostic imaging agents that can
sensitivity of the compounds, as a precaution all reaction vessels
also deliver therapy [27] and we herein report the first
were wrapped in foil. The successful synthesis of both L1 and L2
investigation into the anticancer properties and cell imaging was confirmed using 1H, 13C{1H} NMR and IR (two distinct
capabilities of metal complexes incorporating the anthracene-1,9- carbonyl stretches at ca. 1680 and 1650 cm-1) spectroscopies. HR
dicarboximide fluorophore. mass spectrometry showed the [M]+ parent ion for L2, and [M+H]+
and [M+Na]+ cations for L1.
The rhenium precursor complex fac-[Re(CO) (MeCN) ]BF was
3 3 4
reacted with the ligands in chloroform to give fac-
[Re(CO) (L1)]BF and fac-[Re(CO) (L2)]BF . 1H NMR
3 4 3 4
spectroscopy showed a subtle shift in the imide N–CH
2
upon
coordination, while the pyridyl methylene signal revealed a
pronounced and characteristic appearance (SI, Fig S2) as a set
of diastereotopic protons with a 2J geminal coupling [29] (16–17
HH
Results and Discussion Hz). This is consistent with the formation of a rigid, facially
capping chelating ligand. The observation of two CO stretching
frequencies in the IR spectra of both complexes (ca. 2030 and
Synthesis and Characterization 1905 cm-1) further supported the facially capped Re(I) geometry
(consistent with an assumed pseudo C symmetry at Re).
3v
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Furthermore, high resolution mass spectrometry confirmed the studies on Re(I) complexes of amino-substituted naphthalimides
formulation of the complexes, showing [M]+ with the correct where the excited state is ICT dominated.[10,11]
185/187Re isotopic pattern in both cases.
Table 1. Luminescence properties of the ligands and complexes.
Compound [a] lem / nm[a, b] t / ns[c] F[a,d]
L1 489 3.3, 10.6 -
L2 490 16.0 -
[Re(CO)(L1)]BF 489 6.7 0.36
3 4
[Re(CO)(L2)]BF 489 14.5 0.19
3 4
[a] MeCN; [b] λ = 425 nm, 5 × 10-5 M; [c] λ = 459 nm; [d] using
exc exc
[Ru(bipy)
3
](PF
6
)
2
in aerated MeCN as standard (F = 0.016).[32]
Figure 1. UV–vis absorption profiles of the ligands and complexes in MeCN at 2.5 ×
10-5 M. Inset shows an expansion of the visible region for L1.
In photophysical studies, solutions of L1 and L2 were found to be
highly emissive (Fig 1, Table 1) as aerated MeCN solutions. Using
The solution state absorption spectra of L1 and L2 (Fig 1) were an excitation wavelength of 345–425 nm, L1–2 revealed a visible
recorded as MeCN solutions at 2.5 × 10-5 M and were closely emission band peaking at 490 nm, with a lower energy shoulder
comparable to related literature examples that are based on the at 510 nm (Fig 1), which are assigned to the anthracene-1,9-
anthracene-1,9-dicarboximide chromophore.[30] Both ligands dicarboximide fluorophore. The corresponding excitation spectra
showed two strong (ε >104 M-1cm-1) π–π* transitions in the UV revealed a band at 265 nm with an additional, weaker, structured
region at 200-300 nm. In addition, a weaker (ca. ε = 8000 M-1cm- lower energy excitation band between 350–500 nm (Fig 1) that
1), broad and moderately structured low energy π–π* transition closely correlates with the observations from the UV-vis studies.
was also observed at 350–480 nm. It is also likely that n–π* The emitting state of L1–2 is assigned to 1π–π* character, with
transitions occur in this region, but possess lower molar examples showing weak vibronic structure consistent with the
absorption coefficients. As expected, the length of the saturated rigid anthracene core. Time-resolved luminescence data was also
alkyl linker had little effect on the absorption properties. The collected and both ligands showed lifetimes of <20 ns (Table 1),
comparison to more common naphthalimide analogues [31] consistent with fluorescence (1π–π*). The data for L1 best fit to a
shows that the extended π–system of L1 and L2 results in a bi–exponential decay, with a minor quenched species (3.3 ns,
bathochromically shifted π–π* absorption profile. 34 %) and major, longer component (10.6 ns, 66 %). On the other
hand, the lifetime of L2 was shown to be single component and
relatively extended compared to L1.
Luminescence data for fac-[Re(CO) (L)]BF showed that
3 4
coordination of the ligands to Re(I) had minimal effect upon the
excitation and emission profiles (Fig 1) which were clearly ligand-
dominated in both cases, although a minor shortening of the
lifetimes was observed (Table 1). Both complexes displayed
excellent quantum yields at 36 % and 19 % for fac-
[Re(CO) (L1)]BF and fac-[Re(CO) (L2)]BF , respectively. The
3 4 3 4
luminescence studies revealed that the ligands and complexes
should be ideally suited to confocal fluorescence microscopy.
Anticancer properties and cell imaging studies
Figure 2. Excitation (dashed) and emission (solid) spectra of L2 and corresponding
Re(I) complex in MeCN at 5 × 10-5 M (λ = 425 nm).
exc
UV-vis spectroscopy on [Re(CO) (L)]BF were almost identical to
3 4
the free ligands. The lack of perturbation by the cationic Re(I)
complex unit again suggests electronic transitions that are
dominated by π–π* transitions and contrasts with our previous
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Confocal fluorescence microscopy was conducted to assess the
cell imaging capability of these new fluorophores. The
compounds were incubated with Schizosaccharomyces pombe
Table 2. Cytotoxicity IC 50 (µM) values of the ligands and (S. pombe - fission yeast cells) and MCF7 breast cancer cells.
complexes.[a]
The uptake for L1 and L2 into S. pombe was substantially
Compound [a] LOVO A549 PC3 MCF7 improved once higher incubation concentrations were utilized and
resulted in bright emission. L1 had the better uptake into all cells,
L1 5.32 6.46 8.72 1.92
showing the advantageous lipophilicity of the hexyl chain, and
(0.14) (1.27) (0.94) (0.40) revealed distinct foci of staining. Lambda scans for imaged cells
revealed an emission profile consistent with the presence of the
L2 29.25 55.37 66.14 57.41
fluorophore. For MCF7 cells, L1 again revealed bright emission
(2.76) (5.44) (4.65) (1.30) with a small amount of precipitate. General cytoplasmic labeling
[Re(CO)(L1)]BF 7.84 75.04 7.54 6.20 was observed with distinct foci of emission. No nuclear
3 4
penetration was observed, which we have also noted for amino-
(0.26) (0.55) (0.50) (0.16)
substituted naphthalimide fluorophores,[10] but faint membrane
[Re(CO)(L2)]BF 5.74 6.02 6.31 6.05 staining revealed slight membrane blebbing, possibly indicating
3 4
cell apoptosis, consistent with the cytotoxicity data for L1 (IC <2
(0.40) (0.39) (0.28) (0.40) 50
µM vs MCF7). Imaging of MCF7 cells with L2 was not as
successful with reduced uptake and precipitate sitting around or
[a] using MTT assay; standard deviation given in on top of the cells.
parentheses.
Before assessment of the cell imaging capabilities, the ligands
and complexes were analysed for cytotoxicity effects using the
standard MTT assay against LOVO (colon adenocarcinoma),
A549 (lung adenocarcinoma), PC3 (prostate adenocarcinoma)
and MCF7 (breast adenocarcinoma) cell lines. The IC values
50
obtained from these assays are shown in Table 2. From the
results it is clear that all compounds show a strong degree of
toxicity to the four cancer cell lines, although not at the very high
Figure 4. Confocal fluorescence microscopy images of S. pombe yeast cells
potency demonstrated by azonafide (IC <0.1 µM vs MCF7).[33]
50
L2 appears to be the least toxic compound, whilst L1 is the most with fac-[Re(CO) 3 (L2)]BF 4 showing: (left) green fluorescence from the complex
toxic, particularly with MCF7, which may be attributable to the (λ exc = 405 nm; λ em = 480–540 nm) and (right) transmitted light image.
greater lipophilicity of the latter. It is noteworthy that the anticancer
potency of the ligands is generally retained (L1) or enhanced (L2)
upon complexation to Re(I). Thus, the effect of complexation was
For the complexes, significant differences were observed for the
more pronounced for L2, with the resultant complex showing IC
50 imaging capability and cellular localization characteristics. Firstly,
values around 6 µM for all four cell lines. Interestingly for fac-
in S. pombe, fac-[Re(CO) (L1)]BF showed weaker emission than
[Re(CO) (L1)]BF the toxicity towards A549 cells was reduced by 3 4
3 4
an order of magnitude versus the other cell lines. L1; whilst fac-[Re(CO) 3 (L1)]BF 4 was taken up by most of the cells,
the faint emission revealed little detail. Imaging studies on the S.
pombe cells showed a viable population count of 84 % after
imaging against the unstained control. fac-[Re(CO) (L2)]BF was
3 4
only seen to label a subset of cells, possibly indicating organisms
at a specific cell division cycle stage (SI, Fig. S4-S5) that was
supported by the observation of ruffled membranes.
During the S. pombe imaging with fac-[Re(CO) (L2)]BF , studies
3 4
showed extensive red/green channel bleed-through, consistent
with a broad emission peak from the fluorophore. This was further
supported with a Lambda scan (SI, Fig. S6) revealing a
broadened peak at ca. 545 nm (cf Table 1). Similar behaviour is
Figure 3. Confocal fluorescence microscopy images of MCF7 cells with L1
showing: (left) green fluorescence from L1 (λ = 405 nm; λ =480–560 nm) known for the commercially available JC-1, a fluorophore that
exc em
and (right) transmitted light image. localizes within mitochondria by a reversible two-stage
accumulation across plasma membranes and mitochondrial inner
membranes, dependent on their electrochemical potentials.[34]
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JC-1 produces green fluorescence as a monomer and red
fluorescence upon J-aggregate formation that occurs in high
potential membranes.[35] For comparison, the uptake of JC-1 by
S. pombe was relatively poor (SI, Fig. S7), but did allow direct
observation of the dual green/red emission via the different
wavelength detection ranges.
Figure 6. Confocal fluorescence microscopy images of MCF7 cells imaged
using the Re(I) fluorophores. Left: with fac-[Re(CO)(L2)](BF) showing both
3 4
nucleoli; center: with fac-[Re(CO)(L2)](BF) showing membrane staining; right:
3 4
with fac-[Re(CO)(L1)](BF) showing vacuoles or vesicles (all images λ =405
3 4 exc
nm; λ =480–540 nm).
em
Conclusions
In this paper we have shown that anthracene-1,9-dicarboximide
ligand derivatives can be developed as fluorescent cell imaging
probes. All compounds show anticancer potency, although at a
level reduced from that of azonafide. Initial studies, showed that
Figure 5. Concentration dependent emission of fac-[Re(CO)(L2)]BF in MeCN the cytotoxicity and cell imaging capability may be dependent
3 4
(using λ = 425 nm). upon the subtle variations in the ligand structure and the overall
exc
lipophilicity of the fluorophores. Further co-localisation studies are
required to elucidate the intracellular behaviour. Future studies
The potential of aggregation was investigated via concentration will also assess the toxicity of these and related species against
dependent fluorescence studies on fac-[Re(CO) (L2)]BF . non-cancerous cell lines and attempt to identify the mode of action
3 4
Spectra (Fig. 5) revealed a reversible, bathochromic shift (from of this new class of complex.
490 nm to ca. 680 nm) upon increasing concentration (5.0 × 10-5
M to 2.9 × 10-2 M). The spectroscopic studies suggest that an
emission peak at 545 nm (cf microscopy lambda scan) Experimental Section
corresponds to a concentration of ca. 5.0 × 10-3 M for the complex.
The reversibility (upon dilution) of this aggregation negates the
possibility of photoreactivity and/or photocyclisation of the Cell incubation and confocal microscopy
anthracene-1,9-dicarboximide core. While these observations are
reminiscent of the excimer formation in polyaromatic compounds
such as pyrene and anthracene, it is notable that the fluorophores
The fission yeast Schizosaccharomyces pombe 972 h- was grown in 20
in this study present very large bathochromic shifts.
mL medium containing glucose (1%), peptone (1%), and yeast extract
(0.3%) in Ehrlenmeyer flasks shaken at 30°C for 2 days, when glucose
utilisation was complete. Washed once in PBS (phosphate-buffered saline,
Imaging of MCF7 cells with fac-[Re(CO) (L1)]BF and fac-
3 4 pH 7.4) after centrifugation at 1000 g for 2 min, they were incubated 30
[Re(CO) 3 (L2)]BF 4 showed that some of the stained cells had an min with fluorophores in DMSO at 100 µg.mL-1 (final concentrations in
unhealthy 'foamy' appearance with some membrane blebbing,
growth medium) at 20°C before washing again in PBS. JC-1 was used at
indicating apoptosis. This is consistent with the cytotoxicity data 10 µg.mL-1. Human MCF7 adenocarcinoma breast cancer cells (from
showing relatively low IC values for MCF7. However, fac-
50 European Collection of Cell Cultures, Porton Down, Wiltshire, UK) were
[Re(CO) (L1)]BF again showed very bright green emission that
3 4 maintained by subculture every five days in Dulbeco’s Modified Eagle’s
revealed many round intracellular structures with stained
medium plus 10% foetal bovine serum, penicillin and streptomycin.
membranes (Fig 6). Uptake of fac-[Re(CO) (L2)]BF into MCF7
3 4 Detached from the plastic flasks using trypsin EDTA solution, they were
was much improved when compared to L2, presumably due to
washed and re-suspended in excess volume of growth medium. The cell
the overall cationic charge of the complex.[36] fac-
suspensions were distributed into 1 mL aliquots: fluorophores in DMSO at
[Re(CO) (L2)]BF was seen to stain the plasma and nuclear
3 4 100 µg.mL-1 (final concentrations in growth medium). Preparations were
membranes (Fig 6) in a similar fashion to L1. Thus, despite the
viewed by epifluorescence and transmitted light (Nomarski differential
comparable cytotoxicities of the agents, different MCF7
interference contrast optics) using a Leica TCS SP2 AOBS confocal laser
localization patterns were observed from the two complexes.
microscope (Leica, Germany) using ´63 or ´100 objectives, ´4 zoom
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European Journal of Inorganic Chemistry 10.1002/ejic.201601271
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factor and laser power of 20 %. Excitation of the fluorophore was at 405 and the data fits yielded the lifetime values using the provided DAS6
nm using a diode laser, with detection between 480–540 nm (and 630– deconvolution software. Quantum yield measurements were obtained on
690 nm to probe red emission). Initial imaging yielded minimal aerated MeCN solutions of the complexes using [Ru(bpy)](PF) in
3 62
fluorescence so the concentration of the fluorophore was increased to 100 aerated MeCN as a standard (Φ = 0.016).[32]
μg.mL–1 final concentration, which was then incubated with the cells at
room temperature for a further 30 minutes.
All reactions were performed with the use of vacuum line and Schlenk
techniques. Reagents were commercial grade and used without further
Cytotoxicity assessment via MTT assay purification. fac-[Re(CO)(MeCN)]BF [38] and N-Boc-
3 3 4
ethylenediamine,[39] and bis(pyridin–2–ylmethyl)ethane–1,2–diamine [40]
were prepared according to the literature.
The cytotoxicity of the complexes was assessed using the colorimetric and
quantitative MTT [3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium
bromide] assay, first reported by Mosmann.[37] Quantification was Synthesis of (N–1',6'–diaminohexyl)–anthracene–1,9–dicarboximide
achieved using a multi-well scanning spectrophotometer and reported as (N1)
an IC value.
50
1,6–diaminohexane (0.61 mL, 4.66 mmol) was added to anthracene–1,9–
Method for cytotoxicity analysis dicarboxylic anhydride (289 mg, 1.16 mmol) in EtOH (10 mL) and heated
at reflux, under a nitrogen atmosphere for 48 hours. After cooling the
ethanol was removed in vacuo and the product dissolved in minimal
Anti-tumor evaluation in MCF7, LOVO, A549 and PC3 cell lines was chloroform. Water was added and the product neutralized with 1M HCl
performed by MTT assay. Compounds were prepared as 0.1–100 mM after which the mixture was paper filtered into a separating funnel. The
stock solutions dissolved in DMSO and stored at -20 °C. Cells were crude product was washed with copious amounts of water, dried over
seeded into 96-well microtitre plates at a density of 5 × 103 cells per well MgSO 4 and filtered. The solvent was reduced to a minimal volume, and
and allowed 24 h to adhere. Decimal compound dilutions were prepared precipitation was induced with diethyl ether, allowing subsequent filtration
in medium immediately prior to each assay (final concentration 0.1–100 and drying to afford the intermediate product N1 as a brown solid. Yield:
µM). Experimental medium was DMEM +10% FCS (PC3 and Lovo) or 153 mg, 36 %. 1H NMR (400 MHz, CDCl 3 ): δ H = 9.79 (d, 1H, 3J HH = 9.1
RPMI +10% heat inactivated FCS (A549 and MCF7). Following 96 h Hz), 8.56 (d, 1H, 3J HH = 7.0 Hz), 8.53 (s, 1H), 8.12 (d, 1H, 3J HH = 8.4 Hz),
compound exposure at 37 °C, 5% CO 2 , MTT reagent (Sigma Aldrich) was 7.90 (d, 1H, 3J HH = 8.4 Hz), 7.69 (app. t, 1H, 3J HH = 7.0 Hz), 7.56 (dd, 1H,
added to each well (final concentration 0.5 mg/ml). Incubation at 37 °C for J HH = 8.5, 6.9 Hz), 7.50 (app. t, 1H, 3J HH = 7.9 Hz), 4.15 (t, 2H, 3J HH = 7.8
4 h allowed reduction of MTT by viable cells to an insoluble formazan Hz, CH 2 ), 2.69–2.60 (broad m, 2H), 1.83–1.69 (broad m, 4H), 1.57–1.35
product. MTT was removed and formazan solubilized by addition of 10% (broad m, 4H) ppm.
Triton X-100 in PBS. Absorbance was read on a Tecan Sunrise
spectrophotometer at 540 nm as a measure of cell viability; thus inhibition
relative to control was determined (IC 50 ) from four independent sets of data Synthesis of (N’,N’–bis(pyridin–2–ylmethyl) hexyldiamine)–
and the standard deviations calculated from these data sets. anthracene–1,9–dicarboximide (L1)
General N1 (0.117 g, 0.34 mmol) was added to a solution of 2–
pyridinecarboxaldehyde (0.1 mL, 0.98 mmol) in 1,2–dichloroethane (5 mL)
and stirred for 2 hours at room temperature under a nitrogen atmosphere.
1H and 13C-{1H} NMR spectra were recorded on an NMR-FT Bruker 400 Sodium triacetoxyborohydride (0.214 g, 1.01 mmol) was then added, and
and 250 MHz spectrometer and recorded in CDCl. 1H and 13C{1H} NMR the mixture was stirred for a further 4 days. The solution was then
3
chemical shifts (δ) were determined relative to residual solvent peaks with neutralized with saturated aq. NaHCO 3 , and the product was extracted
digital locking and are given in ppm. Low-resolution mass spectra were using CHCl 3 . The organic layer was washed with water (3 × 25 mL) and
obtained by the staff at Cardiff University. High-resolution mass spectra brine (2 × 25 mL) and then dried over MgSO 4 . Following filtration, the
were carried out at the EPSRC National Mass Spectrometry Facility at solvent was reduced in vacuo and purified via column chromatography,
Swansea University. UV-Vis studies were performed on a Jasco V-570 washed with dichloromethane and eluted with a 95:5 mixture of
spectrophotometer as MeCN solutions (2.5 or 5 × 10-5 M). Photophysical DCM:MeOH. Removal of the solvent in vacuo afforded L1 as a brown oil.
data were obtained on a JobinYvon–Horiba Fluorolog spectrometer fitted Yield: 62 mg, 27 %. 1H NMR (400 MHz, CDCl 3 ): δ H = 9.94 (d, 1H, 3J HH =
with a JY TBX picosecond photodetection module as MeCN solutions. 9.1 Hz), 8.73 (s, 1H), 8.69 (dd, 1H, 3J HH = 7.1 Hz, 3J HH = 7.0 Hz), 8.52–
Emission spectra were uncorrected and excitation spectra were instrument 8.47 (m, 2H), 8.28 (d, 1H, 3J HH = 7.8 Hz), 8.05 (d, 1H, 3J HH = 8.4 Hz), 7.79
corrected. The pulsed source was a Nano-LED configured for 459 nm (dd, 1H, 3J HH = 6.7, 6.6 Hz), 7.68–7.49 (m, 6H), 7.12–7.04 (m, 2H), 4.19 (t,
output operating at 1 MHz. Luminescence lifetime profiles were obtained 2H, 3J HH = 7.7 Hz, CH 2 ), 3.78 (s, 4H), 2.56–2.48 (m, 2H), 1.80–1.65 (broad
using the JobinYvon–Horiba FluoroHub single photon counting module m, 2H), 1.65−1.51 (broad m, 2H), 1.44–1.32 (broad m, 4H) ppm; 13C{1H}
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NMR (75 MHz, CDCl): δ = 165.3 (CO), 163.8 (CO), 149.1, 136.6, 136.4, Prepared as for fac–[Re(CO)(L1)]BF using fac-[Re(CO)(MeCN)]BF
3 C 3 4 3 3 4
134.9, 133.6, 133.5, 132.7, 131.4, 129.9, 129.0, 128.6, 127.8, 127.4, 127.3, (83 mg, 0.17 mmol) and L2 (82 mg, 0.17 mmol) to give fac–
126.9, 126.6, 125.6, 123.1, 122.1 ppm; HRMS (ES+) found m/z 529.2588; [Re(CO)(L2)]BF as a yellow powder. Yield = 88 mg, 67 %. 1H NMR (400
3 4
calculated 529.2598 for [C H NO]+. IR (solid) ν = 1685, 1647 cm−1. MHz, (CDCN): δ = 9.62 (d, 1H, 3J = 9.7 Hz), 8.88 (s, 1H), 8.72 (d, 1H,
34 33 4 2 CO 3 H HH
UV−Vis (MeCN): λ (ε/M−1 cm−1) = 457 (3100), 433 (4500), 406 (3300), J = 7.0 Hz), 8.62 (d, 2H), 8.38 (d, 1H, 3J = 8.0 Hz), 8.17 (d, 1H, 3J =
max HH HH HH
378 (4100), 360 (1900), 265 (56600) nm. 8.0 Hz), 7.92–7.75 (m, 5H), 7.72 (app. t, 1H), 7.61 (app. t, 1H), 7.31–7.11
(m, 2H, overlapping with residual CHCl peak), 5.61 (d, 2H, 2J = 16.8 Hz,
3 HH
1/2 × 2CH), 4.84 (overlapping m, 4H, including d, 2H, 2J = 16.8 Hz, 1/2
2 HH
Synthesis of (N’,N’–bis(pyridin–2–ylmethyl)ethyldiamine)– × 2CH 2 ), 4.1 (t, 2H, 3J HH = 6.2 Hz, CH 2 ) ppm. 13C{1H} NMR (150 MHz,
anthracene–1,9–dicarboximide (L2) CD 3 CN): δ C = 196.1 (CO), 194.8 (CO), 165.2 (CO), 163.7 (CO), 160.2,
152.2, 140.5, 137.6, 136.0, 133.8, 133.3, 132.4, 131.8, 130.3, 129.0, 128.5,
126.6, 126.0, 125.8, 125.7, 123.7, 123.6, 122.2, 67.8, 66.7, 36.3 ppm.
Prepared as for N1 but using bis(pyridin–2–ylmethyl)ethane–1,2–diamine HRMS (EI+) found m/z = 743.1290; calculated 743.1300 for
(106 mg, 0.50 mmol) and anthracene–1,9–dicarboxylic anhydride (122 mg, [C 41 H 40 N 4 O 5 Re]+. IR (solid) ν CO = 2033, 1906, 1719, 1690 cm-1. UV-vis
0.50 mmol) with heating for 72 hours to afford L2 as a dark orange powder. (MeCN): λ max (ε /M-1cm-1) = 436 (3200), 202 (29800), 262 (33400), 355
Yield = 123 mg, 98 %. 1H NMR (400 MHz, CDCl): δ = 9.90 (d, 1H, 3J (1700), 377 (3000) nm.
3 H HH
= 9.9 Hz), 8.87 (s, 1H), 8.68 (d, 1H, d, 3J = 7.6 Hz), 8.39 (d, 1H, 3J =
HH HH
9.3 Hz), 8.35 (d, 2H, 3J = 3.3 Hz), 8.14 (d, 1H, 3J = 7.7 Hz), 7.80 (app.
HH HH
t, 1H, 3J = 7.2 Hz), 7.75 (app. t, 1H, 3J = 7.8 Hz), 7.65 (app. t, 1H, 3J Acknowledgements
HH HH HH
= 7.2 Hz), 7.22 (d, 2H, 3J = 9.3 Hz), 7.09 (app. t, 2H, 3J = 7.2 Hz), 6.87
HH HH
(app. t, 2H, 3J HH = 6.0 Hz), 4.51 (t, 2H, 3J HH = 6.2 Hz, CH 2 ), 3.90 (s, 4H, We thank Cardiff University for financial support and the staff of
CH 2 ), 2.97 (t, 2H, 3J HH = 6.2 Hz, CH 2 ) ppm; 13C{1H} NMR (75 MHz, CDCl 3 ) the EPSRC Mass Spectrometry National Service (University of
δ C = 165.0 (CO), 163.6 (CO), 159.8, 148.8, 136.4, 136.2, 135.1, 133.7, Swansea) for providing MS data.
133.5, 132.6, 131.3, 129.8, 128.9, 128.4, 127.0, 126.6, 125.6, 122.9, 122.7,
77.6, 77.2, 76.7, 60.4, 52.0, 38.1 ppm. HRMS (EI+) found m/z = 473.1967;
Keywords: fluorescence • cell imaging • rhenium • azonafide •
calculated 473.1972 for [C H NO]+. IR (solid) ν = 1680, 1660 cm-1.
38 40 4 2 CO anticancer
UV-vis (MeCN): λ (ε /M-1cm-1) = 428 (7300), 373 (9000), 360 (3800),
max
265 (79600), 219 (28900) nm.
[1] See: The Chemistry of Molecular Imaging Eds. N. Long, W-T. Wong,
Wiley: New Jersey, 2015 and references therein.
[2] O.F. Ikotun, S.E. Lapi, Future Med. Chem. 2011, 3, 599-621.
Synthesis of fac–[Re(CO)(L1)]BF [3] J.R. Dilworth, P.S. Donnelly, in Therapeutic Rhenium
3 4
Radiopharmaceuticals – In Metallotherapeutics – The Use of Metal-
Based Drugs in Medicine, 2005, 463; A.R. Cowley, J.R. Dilworth, P.S.
Donnelly, S.J. Ross, Dalton Trans. 2007, 73-82; B. Lambert, K. Bacher,
L1 (63 mg, 0.12 mmol) and fac–[Re(CO)(MeCN)]BF (54 mg, 0.14 mmol)
3 3 4 L. Defreyne, J. Nucl. Med. Mol. Imaging 2009, 53, 305-310; Dilworth,
were dissolved in CHCl (10 mL) and heated at reflux under a nitrogen
3 J.R.; Parrott, S.J.; Chem. Soc. Rev. 1998, 27, 43-55; P.J. Blower, J.R.
atmosphere for 12 hours. Reaction progression was monitored by a 14:2:1 Dilworth, R.I. Maurer, G.D. Mullen, C.A. Reynolds, Zheng, J. Inorg.
mix of HO:MeCN:sat. KNO. Upon completion the reaction mixture was Biochem. 2001, 85, 15-22; R. Alberto, K. Ortner, N. Wheatley, R. Schibli,
2 3
allowed to cool, the solvent was reduced to 1−2 mL, and precipitation was P.A. Schubiger, J. Am. Chem. Soc. 2001, 123, 3135-3136
[4] J.M. Jeong, J-K. Chung, Cancer Biother. Radiopharm. 2004, 18, 707-
induced with the addition of diethyl ether. The product was collected by
717; Chen, Y.; Xiong, Q-F.; X-Q. Yang, L. He, Z-W. Huang, Am. J.
filtration and washed with diethyl ether, to give fac-[Re(CO)(L1)]BF as a
3 4 Roentgen. 2010, 194, 761-765; B. Lambert, J.M. de Klerk, Nucl. Med.
yellow solid. Yield: 61.0 mg, 61 %. 1H NMR (400 MHz, (CDCl): δ = 10.01
3 H Commun. 2006, 27, 223-229.
(d, 1H, 3J HH = 9.6 Hz), 8.87 (s, 1H), 8.78 (dd, 1H, J HH = 7.2, 7.1 Hz), 8.68– [5] S.L. Pimlott, A. Sutherland, Chem. Soc. Rev. 2011, 40, 149-162.
8.65 (m, 2H), 8.39 (d, 1H, 3J HH = 8.0 Hz), 8.14 (d, 1H, 3J HH = 8.0 Hz), 7.85– [6] K.A. Stephenson, S.R. Banerjee, T. Besanger, O.O. Sogbein, M.K.
7.74 (m, 7H), 7.24–7.19 (m, 2H), 5.27 (d, 2H, 2J = 16.8 Hz, 1/2 × 2CH), Levadala, N. McFarlane, J.A. Lemon, D.R. Boreham, K.P. Maresca, J.D.
HH 2
4.43 (d, 2H, 2J = 16.4 Hz, 1/2 × 2CH), 4.31 (t, 2H, 3J = 8.0 Hz, CH), Brennan, J.W. Babich, J. Zubieta, J.F. Valliant, J. Am. Chem. Soc. 2004,
HH 2 HH 2
126, 8598-8599; A.F. Armstrong, J.M. Lebert, J.D. Brennan, J.F. Valliant,
3.79–3.68 (broad m, 2H), 2.14–1.99 (broad m, 2H), 1.93–1.81 (broad m,
Organometallics 2009, 28, 2986-2992; D.K. Emerson, K.K. Limmer, D.J.
2H), 1.68−1.49 (broad m, 4H) ppm. HRMS (ES+) found m/z 799.1917;
Hall, S-H. Han, W.C. Eckelman, C.J. Kane, A.M. Wallace, D.R. Vera,
calculated 799.1927 for [C H NORe]+. IR (solid) ν = 2027, 1904,
37 32 4 5 CO Radiology 2012, 265, 186-193; Y. Yang, L. Zhu, M. Cui, R. Tang, H.
1645, 1610 cm−1. UV−Vis (MeCN): λ max (ε/M−1cm−1) = 456 (4200), 432 Zhang, Bioorg. Med. Chem. Lett. 2010, 20, 5337-5344; F.L. Thorp-
(5900), 408 (4400), 377 (5200), 359 (2600), 264 (40000), 243 (36000), 236 Greenwood, M.P. Coogan, Dalton Trans. 2011, 40, 6129-6143; P.
(34300) nm. Hafliger, N. Agorastos, B. Spingler, O. Georgiev, G. Viola, R. Alberto,
ChemBioChem 2005, 6, 414-421; V. Polyakov, V. Sharma, J.L.
Dahlheimer, C.M. Pica, G.D. Luker, D. Piwnica-Worms, Bioconj. Chem.
2000, 11, 762-771; K.P. Maresca, S.M. Hillier, F.J. Femia, C.N.
Synthesis of fac–[Re(CO)(L2)]BF
3 4 Zimmerman, M.K. Levadala, S.R. Banerjee, J. Hicks, C. Sundararajan,
J. Valliant, J. Zubieta, W.C. Eckelman, J.L. Joyal, J.W. Babich, Bioconj.
Chem. 2009, 20, 1625-1633; M. Sagnou, S. Tzanopoulou, C.P.
For internal use, please do not delete. Submitted_Manuscript
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Raptopoulou, V. Psycharis, H. Braband, R. Alberto, I.C. Pirmettis, M. [23] S. Bear, W.A. Remers, J. Computer-Aided Mol. Des. 1996, 10, 165-175.
Papadopoulous, M. Pelecanou, Eur. J. Inorg. Chem. 2012, 4279-4286. [24] S. M. Sami, R. T. Dorr, D. S. Alberts, A. M. Sólyom, W. A. Remers, J.
[7] S.S. Kelkar, T.M. Reineke, Bioconjugate Chem. 2011, 22, 1879-1903; R. Med. Chem. 1996, 39, 4978-4987
Kumar, W.S. Shin, K. Sunwoo, W.Y. Kim, S. Koo, S. Bhuniya, J.S. Kim, [25] H. Langhals, G. Schonmann, K. Polborn, Chem. Eur. J. 2008, 14, 5290-
Chem. Soc. Rev. 2015, 44, 6670-6683. 5303.
[8] N. Agorastos, L. Borsig, A. Renard, P. Antoni, G. Viola, B. Spingler, P. [26] C. A. Mayr, S. M. Sami, W. A. Remers, R. T. Dorr, Anti-Cancer Drugs
Kurz, R. Alberto, Chem. Eur. J. 2007, 13, 3842-3852. 1999, 10, 163-170.
[9] P. Haefliger, N. Agorastos, A. Renard, G. Giambonini-Brugnoli, C. Marty, [27] L.E. Jennings, N.J. Long, Chem. Commun. 2009, 3511-3524; S.
R. Alberto Bioconjugate Chem. 2005, 16, 582-587. Faulkner, N.J. Long, Dalton Trans. 2011, 40, 6067; F.L. Thorp-
[10] E.E. Langdon-Jones, N.O. Symonds, S.E. Yates, A.J. Hayes, D. Lloyd, Greenwood, M.P. Coogan, Dalton Trans. 2011, 40, 6129-6143.
R. Williams, S.J. Coles, P.N. Horton, S.J.A. Pope, Inorg. Chem. 2014, [28] J. H. Yao, C. Chi, J. Wu, K-P. Loh, Chem. Eur. J. 2009, 15, 9299-9302
53, 3788-3797 [29] L. A. Mullice, R. H. Laye, L. P. Harding, N. J. Buurma, S. J. A. Pope, New
[11] E.E. Langdon-Jones, D. Lloyd, A.J. Hayes, S.D. Wainwright, H.J. J. Chem. 2008, 32, 2140-2149
Mottram, S.J. Coles, P.N. Horton, S.J.A. Pope, Inorg. Chem. 2015, 54, [30] J. Gawroński, K. Gawrońska, P. Skowronek, A. Holmén, J. Org. Chem.
6606-6615. 1999, 64, 234-241
[12] I. Ott, Y. Xu, J. Liu, M. Kokoschka, M. Harlos, W.S. Sheldrick, X.H. Qian, [31] S. Banerjee, E.B. Veale, C.M. Phelan, S.A. Murphy, G.M. Tocci, L.J.
Bioorg. Med. Chem. 2008, 16, 7107-7116. Gillespie, D.O. Frimannsson, J.M. Kelly, T. Gunnlaugsson, Chem. Soc.
[13] D. Rideout, R. Schinazi, C. D. Pauza, K. Lovelace, L. C. Chiang, T. Rev. 2013, 42, 1601-1618.
Calogeropoulou, M. McCarthy, J. H. Elder, J. Cell. Biochem. 1993, 51, [32] M. Frank, M. Nieger, F. Vogtle, P. Belser, A. von Zelewsky, L. de Cola,
446-457 V. Balzani, F. Barigelletti, L. Flamigni, Inorg. Chim. Acta 1996, 242,
[14] B-Y. Liu, W-W. Wu, N. Wang, X-Q. Yu, Polym. Chem. 2015, 6, 364-368. 281−291
[15] C. Satriano, G.T. Sfrazzetto, M.E. Amato, F.P. Ballistreri, A. Copani, M.L. [33] S.M. Sami, R.T. Dorr, D.S. Alberts, A.M. Solyom, W.A. Remers, J. Med.
Giuffrida, G. Grasso, A. Pappalardo, E. Rizzarelli, G.A. Tomaselli, R.M. Chem. 2000, 43, 3067-3073.
Toscano, Chem. Commun. 2013, 49, 5565-5567; M. Vonlanthen, C.M. [34] in The Molecular Probes Handbook: A Guide to Fluorescent Probes and
Connelly, A. Deiters, A. Linden, N.S. Finney, J. Org. Chem. 2014, 79, Labeling Technologies, Thermo Fisher Scientific Inc., 11th edn., 2010,
6054-6060. ch. 12.2
[16] Y. Dai, B-K. Lv, X-F. Zhang, Y. Xiao, Chin. Chem. Lett. 2014, 25, 1001- [35] S. T. Smiley, M. Reers, C. Mottola-Hartshorn, M. Lin, A. Chen, T. W.
1005. Smith, G. D. Steele Jr., L. B. Chen, Proc. Natl. Acad. Sci. U.S.A. 1991,
[17] S-A. Choi, C.S. Park, O.S. Kwon, H-K. Giong, J-S. Lee, T.H. Ha, C-S. 88, 3671-3675
Lee, Sci. Rep. 2016, 6, 26203. [36] A.J. Amoroso, M.P. Coogan, J.E. Dunne, V. Fernandez-Moreira, J.B.
[18] A. Wu, P. Mei, Y. Xu X. Qian, Chem. Biol. Drug Des. 2011, 78, 941-947; Hess, A.J. Hayes, D. Lloyd, C. Millet, S.J.A. Pope, C. Williams, Chem.
C. A. Mayr, S. M. Sami, W. A. Remers, R. T. Dorr, Drug Metab. Dispos. Commun. 2007, 3066-3068; A.J. Amoroso, R.J. Arthur, M.P. Coogan,
1998, 26, 105-109 J.B. Court, V. Fernandez-Moreira, A.J. Hayes, D. Lloyd, C. Millet, S.J.A.
[19] R.M. Stone, E. Mazzola, D. Neuberg, S.L. Allen, A. Pigneux, R.K. Stuart, Pope, New J. Chem. 2008, 32, 1097-1102; R.G. Balasingham, F.L.
M. Wetzler, D. Rizzieri, H.P. Erba, L. Damon, J-H. Jang, M.S. Tallman, Thorp-Greenwood, C.F. Williams, M.P. Coogan, S.J.A. Pope, Inorg.
K. Warzocha, T. Masszi, M.A. Sekeres, M. Egyed, H-A. Horst, D. Chem. 2012, 51, 1419-1426; V. Fernandez-Moreira, F.L. Thorp-
Selleslag, S.R. Solomon, P. Venugopal, A.S. Lundberg, B. Powell, J. Clin. Greenwood, M.P. Coogan, Chem. Commun. 2010, 46, 186-202; K.K-W.
Oncol. 2015, 33, 1252-1257. Lo, A.W-T. Choi, W.H-T. Law, Dalton Trans. 2012, 41, 6021-6047
[20] G.R. Weiss, H.A. Burris III, J.R. Eckardt, S. Fields, T. O’Rourke, G.I. [37] T. Mosmann, J. Immunol. Methods 1983, 65, 55-63
Rodriguez, M.L. Rothenberg, Cancer Chemother. Biol. Response [38] J.V. Casper, T.J. Meyer, J. Phys. Chem. 1983, 87, 952-957
Modifiers Annu. 1994, 15, 130-151 [39] S.R. Chhabra, A. Mahajan, W.C. Chan, J. Org. Chem. 2002, 67, 4017-
[21] M.F. Braña, J.M. Castellano, C.M. Roldan, A. Santos, A. Jimenez, 4029.
Cancer Chemother. Pharmacol. 1980, 4, 61-66; M. F. Braña, A.M. Sanz, [40] S. Mizukami, S. Okada, S. Kimura, K. Kikuchi, Inorg. Chem. 2009, 48,
J.M. Castellano, C.M. Roldan, C. Roldan, Eur. J. Med. Chem. 1981, 16, 7630-7638.
207-212
[22] S. M. Sami, R. T. Dorr, A. M. Sólyom, D. S. Alberts, W.A. Remers, J.
Med. Chem. 1995, 38, 983-993; M. C. Sharma, S. Sharma, P. Sharma,
A. Kumar, Med. Chem. Res. 2013, 22, 5772-5788
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Fluorescent anthracene-1,9- Emily E. Langdon-Jones, Ariana B.
dicarboximide derivatives have been Jones, Catrin F. Williams, Anthony J.
developed as ligands for Re(I). The Hayes, David Lloyd, Huw J. Mottram,
ligands and complexes show and Simon J.A. Pope*
anticancer behaviour and can be
applied to fluorescence cell imaging Page No. – Page No.
using MCF7 and S. pombe cells. ((Insert TOC Graphic here: max. Anticancer, azonafide-inspired
width: 5.5 cm; max. height: 5.0 cm)) fluorescent ligands and their
rhenium(I) complexes for cellular
imaging
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ytisnetnI
ecnecseroulF
European Journal of Inorganic Chemistry 10.1002/ejic.201601271
MCF7 cell imaging
wavelength/nm
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