Self-assembled vesicle and rod-like aggregates of functionalized perylene diimide: Reaction-based near-IR intracellular fluorescent probe for selective detection of palladium

Article abstract of DOI:10.1039/c6tb00512h

Herein, we report design, synthesis, and self-assembly of perylene diimide (PDI) based near-IR intracellular probe (PS-PDI). PS-PDI molecules undergo aggregation to form self-assembled nanospheres and nanorods morphology in THF:H₂O (1:1) and DM

Full text of DOI:10.1039/c6tb00512h

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DOI: 10.1039/C6TB00512H
Self-assembled vesicle and rod-like aggregates of functionalized perylene
diimide: Reaction based near-IR intracellular fluorescent probe for selective
detection of palladium
Prabhpreet Singh,*a Lalit Singh Mittal,a Vanita Vanita,b Kapil Kumar,a Amandeep Walia,b Gaurav Bhargava,c Subodh
Kumara
aDepartment of Chemistry, UGC Centre for Advanced Studies, Guru Nanak Dev University, Amritsar 143 005, India.
e-mail: prabhpreet.chem@gndu.ac.in; Tel: +91-84271-01534bb
bDepartment of Human Genetics, Guru Nanak Dev University, Amritsar 143 005, India.
cDepartment of Applied Sciences, Punjab Technical University, Kapurthala-144601, Punjab, India.
Nanovesicle and rod-like aggregates of PS-PDI after Pd0 based depropargylation shows de-aggregation
and near-infrared, ratiometric absorbance and emission changes in water, drug, environmental samples
and live HeLa cells.

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Self-assembled vesicle and rod-like aggregates of functionalized
perylene diimide: Reaction based near-IR intracellular fluorescent
probe for selective detection of palladium
Received 00th January 20xx,
Accepted 00th January 20xx
Prabhpreet Singh,*a Lalit Singh Mittal,a Vanita Vanita,b Kapil Kumar,a Amandeep Walia,b Gaurav
Bhargava,c Subodh Kumara
DOI: 10.1039/x0xx00000x
www.rsc.org/
Abstract: Herein, we report design, synthesis and self-assembly of perylenediimide (PDI) based near-IR intracellular probe
(PS-PDI). PS-PDI molecules undergo aggregation to form self-assembled nanospheres and nanorods morphology in
THF:H2O (1:1) and DMSO:H2O (1:9), respectively. The nanospheres have an open hole on surface reminiscent of vesicle
structure (with diameter of internal void in the range of 20-25 nm) whereas length of the nanorods extended up to few µm
range. The Pd0 based depropargylation leads to de-aggregation of these PS-PDI aggregates into smaller spherical
aggregates as evidenced by DLS, SEM and TEM studies. Interestingly, these aggregates of PS-PDI in solution show highly
sensitive behavior in the presence of Pd0 showing absorbance changes in NIR region (λmax = 710 nm) and quenching of
emission at λem 630 nm (DMSO:H2O, 1:9) with limit of detection = 6.6 x 10-9 M or at λem 564 nm (THF:H2O, 1:1) with limit of
detection = 2.1 x 10-8 M. Time and concentration dependent kinetics profiles of PS-PDI aggregates revealed impressive
rate constant value of 0.4 s-1 and 0.21 s-1 (DMSO:H2O, 1:9), respectively in fluorescence and UV-Vis spectroscopy using
2x10-5 M concentration of Pd0. PS-PDI undergoes rapid internalization into HeLa cells with low cytotoxicity and successfully
used as intracellular imaging reagent for Pd0 in live HeLa cell. For practical application, we have exploited these nano-
aggregates of PS-PDI for estimation of Pd2+ in the presence of NaBH4-PPh3 mixture, Pd0 in drug and environmental samples
and Pd2+ in urine sample with excellent selectivity and sensitivity.
has propensity for aggregation in aqueous medium via π-π
stacking, hydrogen bonding, electrostatic and solvation
interactions. Although many reports regarding modification of
1. Introduction
Perylenediimides (PDIs) are well documented class of
functional organic dyes with excellent electronic, optical and
redox properties.1-5 Due to these properties PDIs may find
applications in dyes and pigments industries,6 optoelectronic
devices7-9 and supramolecular chemistry.10-20 The aggregation
and optoelectronic properties of PDIs can be tailored through
modification of its π-molecular structure with chemical
groups1,21-22 either or both at the imide or bay positions of the
PDIs core. Due to presence of planar π-conjugated core, PDI
imide position of PDIs to generate self-assembled
nanostructures are being published each year23-24 however,
little attention has been paid to the self-assembly of bay
substituted PDIs.25-26 Probably, the substitutions at bay
position drastically increase the solubility of PDIs and if
substituents are bulky in nature, the perylene backbone
deviate from planarity to minimize the strain and this hinders
the possibility of π-π stacking. Moreover, the application of
self-assembled PDIs for molecular recognition of metal ions
and anions in water via aggregation or de-aggregation of PDIs
has been scarcely reported due to the poor solubility of PDIs in
aqueous medium. Earlier we have reported (ionic)self-
assembly of benzimidazolium, amino acids and nucleobase-
functionalized carbon nanotubes (CNTs)27-29 and now we
envisage that ease in aggregation of perylene chromophore in
aqueous medium could be exploited for molecular recognition
by using stimuli based aggregation-disaggregation of PDIs. In
this context, we recently synthesized PDI based probe and
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judiciously utilized its aggregation behavior for detection of
perchlorate anion in water and C6 glioma cells.10
Palladium is well known for its role as catalyst in organic
synthesis (drugs) and thus extensively used in pharmaceutical
industry.30 Palladium is also widely used in several materials
such as jewellery, automobiles, dental crowns and fuel cells.
Palladium species can also interact and form complexes with
biomolecules and may interfere with cellular processes.31
Thus, our environment is continuously being polluted with
Palladium that poses serious human and environmental health
hazards. Several conventional analytical methods have been
developed to detect palladium species,32 however ratiometric
Scheme 2. Synthesis of the chemodosimeter PDI 5; Reagents and conditions (a)
cyclohexyl amine, imidazole, 140oC, 4h; (b) ceric ammonium nitrate, H2SO4-HNO3
mixture, RT, 10 min; (c) propargyl alcohol, K2CO3, DMF, 80oC, 2h.
chromo-fluorescent probes with
a convenient operation
On addition of Pd0, the nanovesicles or nanorods assembly
disintegrate to form smaller nanospherical structures.
Amongst PS-PDI and PDI 5, the former show significantly
design principal provide an edge over these methods in terms
of naked eye visibilty, low cost, sensitivity and selectivity.33
Moreover probes showing absorption and emission maxima at
˃600 nm could be beneficial for cellular applications.
higher solubility (better than earlier literature report) and
shows higher sensitivity towards Pd0 using DMSO:H2O (1:9,
where PS-PDI exist in aggregated form) both in absorption and
fluorescence spectrum. Bis(propargyloxy) derivatives DPS-PDI
show equally good solubility in mixed aqueous medium but
lesser change in absorption and fluorescence spectrum was
observed. The PS-PDI has been successfully used for
determination of Pd0 in live HeLa cells through confocal
imaging.
Chemodosimeter, as defined by Chae and Czarnik, is an
abiotic molecule which shows irreversible transduction of an
observable signal on analyte recognition.34 Depropargylation /
deallylation35 of propargyloxy and allyloxy derivatives of
fluorophores and chromophores have provided a general
method for the development of Pd0 selective
chemodosimeters. PDIs due to their electron deficient nature
show large internal charge transfer (ICT) phenomenon in the
presence of electron donating groups, but have found limited
applications in developing Pd0 probes.17 We envisaged that if
the propargyloxy group on PDI undergoes efficient Pd0
depropargylation, it will result in formation of phenoxide
derivatives under physiological conditions and thus would
result in enhanced ICT process and is expected to shift the
absorption band towards longer wavelength.
2. Experimental Section
2.1 Materials and Characterization
Chemicals and solvents were of reagent grade and used
without further purification unless otherwise stated. All
reactions were performed under N2 atmosphere. DMF, DMSO,
and Tetrahydrofuran (THF) solvents were of HPLC grade.
Deionized water was obtained from ULTRA UV/UF Rions Lab
Water System Ultra 370 series. Chromatographic purification
was done with silica gel 60-120 mesh. TLC was performed on
aluminium sheets coated with silica gel 60 F254 (Merck,
In the work reported herein, we have designed new PDI
based mono-propargyloxy derivatives PS-PDI and PDI
5 having
N-(ethylpropyl) and N-cyclohexyl group, respectively at imide
positions and bis-propargyloxy derivative DPS-PDI substituted
with N-(ethylpropyl) group at imide positions. PS-PDI
transformed into nanospheres with an open hole on the
surface in THF:H2O (1:1), whereas it generates nanorods self-
assembly in DMSO:H2O (1:9).
Darmstadt). PDI 136a PDI 210 and PDI 336b were synthesized
,
according to literature procedures. NMR spectra were
recorded on Bruker and JEOL (operating at 500 and 400 MHz
for 1H; 125 and 100 MHz for 13C, respectively). The peak values
were obtained as ppm (δ), and referenced to the TMS as
reference in 1H NMR and deutrated solvent in 13C NMR
spectra. Abbreviations used for splitting patterns are s =
singlet, bs = broad singlet, t = triplet, q = quartet, m =
multiplet. The absorption spectra were recorded on Shimadzu-
2450 spectrophotometer from Shimadzu equipped with Peltier
system as temperature controller. Quartz cells of appropriate
length were used for sample measurement. The spectral
bandwidth and the scan rate were fixed at 2 nm and 140 nm
min-1, respectively. The fluorescence titrations were
Scheme 1. Synthesis of the chemodosimeters PS-PDI and DPS-PDI; Reagents and
conditions (a) propargyl alcohol, K2CO3, DMF, 90oC, 9h.
2 | J. Name., 2012, 00, 1-3
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performed on Varian Carey Eclipse fluorescence δ 9.56 (d, 2H, J = 8.5 Hz, perylene-ArH), 8.60 (d, 2H, J = 8.5
spectrophotometer using slit width (excitation = 10 nm, perylene-ArH), 8.58 (s, 2H, perylene-ArH), 5.18 (d, 4H, J = 2.5
emission = 3 nm) with excitation at 500 nm, unless otherwise Hz, propargyl-CH2), 5.11-5.04 (m, 2H, ethylpropyl), 2.69 (t, J =
stated. Fourier transform infrared (FT-IR) spectra were 2.5, 2H, propargyl -CH), 2.32-2.23 (m, 4H, ethylpropyl), 2.00-
recorded on Perkin Elmer 92035. High resolution mass spectra 1.91 (4H, m, ethylpropyl), 0.94 (t, J = 7.5, 12H, ethylpropyl); 13C
were recorded on a MALDI ultraflex TOF. Confocal microscopy NMR (125 MHz, CDCl3): δ 164.3, 155.4, 133.5, 129.8, 129.3,
imaging was carried out with NIKON AIR confocal laser 129.2, 124.5, 123.9, 122.4, 122.1, 122.0, 118.4, 77.6, 77.3,
scanning microscope using diode laser excitation at 490 nm. 57.9, 57.8, 25.2, 11.5; IR (ATR): ν = 3268, 2975, 2875, 2123,
Imaging was performed with Plan Apo 60X objective lens with 1694, 1658, 1590, 1325, 1232, 1065, 900, 647; HRMS: calcd for
oil-emersion. Dynamic Light Scattering (DLS) measurements C40H34N2O6 (M + H+) 639.24, found 639.67; λabs 550, 521 nm
were performed at 25.0 ± 0.1°C using a light-scattering and λem - 570 nm (THF).
apparatus (Zetasizer Nano ZS Malvern Instrument Ltd., U.K.).
SEM measurements were performed on a ZEISS SUPRATM55
2.4 Synthesis of PDI 4[37a]
operating at an acceleration voltage of 10 KV with tungsten The mixture of PDI
3 (2 g, 3.6 mmol), Ceric ammonium nitrate
filament as electron source. The TEM images were obtained (2.4 g, 4.3 mmol), nitric acid (2.8 mL) and H2SO4 (5 mL) was
with a JEOL JEM-2100 electron microscope operating at an stirred in CHCl3 at room temperature for 10 minutes. The
acceleration voltage of 200 kV.
reaction mixture was then neutralized with water and organic
layer was extracted. The solvent was evaporated under
vacuum and crude product was purified by column
2.2 Synthesis of PS-PDI
A mixture of propargyl alcohol (12.8 mg, 13.3 µL, 0.229 mmol) chromatography (SiO2, chloroform/hexane) to isolate pure PDI
and K2CO3 (47.3 mg, 0.343 mmol) was stirred in dry DMF (2 4, red solid, yield 2.01 gm (3.35 mmol, 93%); Rf = 0.6
mL) under N2 atmosphere. Then, PDI
1
(50 mg, 0.076 mmol) (chloroform/hexane 70:30); 1H NMR (500 MHz, CDCl3, 25 °C): δ
was added and the reaction mixture was stirred at 90oC for 8-9 8.74 (d, 1H, J = 8 Hz), 8.69-8.62 (m, 4H), 8.54 (d, 1H, J = 8.5 Hz),
hours. After cooling to RT, the reaction mixture was poured 8.16 (d, 1H, J = 8 Hz), 5.02-5.01 (m, 2H), 2.55-2.53 (m, 4H),
into ice cold water and the precipitates obtained were filtered. 1.94-1.92 (m, 4H), 1.78-1.76 (m, 8H), 1.49-146 (m, 4H); 13C
After drying under vacuum, crude PS-PDI obtained was further NMR (125 MHz, CDCl3, 25 °C): δ 163.6, 163.3, 163.2, 162.3,
purified by column chromatography (SiO2, Chloroform/ 147.8, 135.5, 133.0, 132.9, 131.4, 131.2, 129.4, 129.3, 129.0,
Hexane) to isolate pure PS-PDI, red colour solid; yield 30 mg 128.0, 127.5, 126.6, 126.5, 126.4, 125.5, 124.8, 124.5, 124.1,
(0.051 mmol, 62.2%); Rf = 0.6 (Chloroform/Hexane 9:1). 1H 123.7, 77.4, 54.7, 54.4, 29.3, 29.2, 26.7, 26.6, 25.6, 25.5.
NMR (500 MHz, CDCl3, 25 °C): δ 9.56 (d, 1H, J = 8.5 Hz,
2.5 Synthesis of PDI 5[37b]
perylene-ArH), 8.68-8.57 (m, 6H, perylene-ArH), 5.23 (d, 2H, J =
2.0 Hz, propargyl -CH2), 5.10-5.05 (m, 2H, ethylpropyl), 2.73 (t, The mixture of propargyl alcohol (18.56 mg, 19.3 µL, 0.331
J = 2.0, 1H, propargyl -CH), 2.30-2.25 (m, 4H, ethylpropyl), mmol), K2CO3 (49 mg, 0.363 mmol) and PDI
4 (100 mg, 0.166
1.99-1.93 (m, 4H, ethylpropyl), 0.96-0.92 (m, 12H, mmol) was stirred in DMF at 80oC for 2 h. After completion of
ethylpropyl); 13C NMR (125 MHz, DMSO-d6): δ 164.6, 156.3, the reaction the solvent was removed under vacuum. The
134.3, 134.0, 133.9, 129.2, 129.0, 128.5, 126.9, 125.0, 123.5, reaction mixture was treated with water and was extracted
122.1, 121.7, 77.9, 77.1, 58.0, 57.8, 57.7, 25.2, 11.5; IR (ATR): ν with CHCl3. The crude product was further purified by column
= 3268, 2965, 2928, 2875, 2121, 1698, 1652, 1591, 1330, 1254, chromatography (SiO2, chloroform/hexane) to isolate pure PDI
1065, 908, 747; HRMS: calcd for C37H32N2O5 (M + H+) 585.23, 5, red solid (0.107 mmol, 65%); Rf = 0.4 (chloroform/ethyl
found 585.776; λabs 543 nm and λem 564 nm (THF).
acetate 96:4); 1H NMR (500 MHz, CDCl3, 25 °C): δ 9.67 (d, 1H, J
= 8.5 Hz), 8.77-8.65 (m, 6H), 5.32 (s, 2H), 5.11-5.06 (m, 2H),
2.73 (s, 1H), 2.59-2.52 (m, 4H), 2.01-1.98 (m, 4H), 1.80-1.88 (m,
2.3 Synthesis of DPS-PDI
To a mixture of propargyl alcohol (73.2 mg, 76 µL, 1.30 mmol) 8H), 1.48-1.55 (m, 4H); 13C NMR (75 MHz, TFA:CDCl3 (1:9), 25
and K2CO3 (270.4 mg, 1.95 mmol) in dry DMF (10 mL) under N2 °C): δ 165.87, 157.44, 135.89, 135.60, 135.28, 133.77, 132.47,
atmosphere was added PDI 2 (300 mg, 0.435 mmol) at RT. The 130.92, 130.21, 129.29, 128.71, 127.17, 125.01, 124.91,
temperature was raised to 80-90oC and reaction continued for 124.02, 123.52, 122.96, 122.90, 122.73, 121.82, 120.68, 78.16,
8-9 hours. After cooling to RT, the reaction mixture was 58.02, 56.57, 56.47, 29.50, 29.47, 26.66, 25.47; λabs 550, 521
poured into ice cold water and the precipitates obtained were nm and λem - 570 nm (THF).
filtered. After drying under vacuum, crude DPS-PDI was
obtained which was further purified by column
3. Results and Discussion
chromatography (SiO2, Chloroform/ Hexane) to isolate pure
DPS-PDI, red colour solid; yield 80 mg (0.125 mmol, 30%); Rf =
0.4 (Chloroform/Hexane 9:1). 1H NMR (500 MHz, CDCl3, 25 °C):
Synthesis
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The bis-propargyloxy substituted perylenediimde DPS-PDI was
synthesized by aromatic nucleophilic substitution reaction of
regio-isomerically pure PDI 210 with propargyl alcohol in DMF
(Scheme 1). As far as chemodosimeter principle is concerned
we proposed that even mono functionalization of PDI can
create desired optical signals in the presence of target analyte.
So, the mono-propargyloxy substituted perylenediimde PS-PDI
was prepared from PDI
described for DPS-PDI (Scheme 1). For the synthesis of PDI
first nitration of PDI has been performed according to
modified procedure. Briefly, PDI was treated with ceric
ammonium nitrate (CAN), with immediate addition of H2SO4-
HNO3 mixture at room temperature to afford PDI in 10 min
in 93% yield. Finally, the reaction between PDI and propargyl
alcohol was performed in DMF using K2CO3 as base to isolate
PDI (Scheme 2). The structure of PDI derivatives have been
1 using the similar protocol as
5,
3
3
4
4
5
unequivocally proved using NMR (1H, 13C) spectroscopic
analysis, FTIR, ESI-MS and photophysical measurements in
solution phase (Fig. S1-S4, ESI).
Fig. 1 UV-Vis absorption changes of PS-PDI after incremental addition of H2O in (a) THF
and (b) DMSO at a concentration of 1x10-5 M; (c) Photographs showing the solubility of
PDI 5 (1-4) and PS-PDI (5-8) in aqueous THF mixture; vial no. 1,5 = THF only; 2,6 = T:H
(7:3); 3,7 = T:H (5:5); 4,8 = T:H (3:7); (d) Photographs showing the solubility of PDI 5 (9-
10) and PS-PDI (11-15) in aqueous DMSO mixture; vial no. 9,12 = D:H (5:5); 10,13 = D:H
(1:9); 11 = T:H (1:9) for comparison purpose; 14,15 = D:H (1:9) but concentration of PS-
Self-assembly and photophysical properties
Although, chemodosimeter PS-PDI and PDI
5 seems to be
hydrophobic by looking at their structures, the presence of
ethylpropyl and cyclohexyl group respectively, at the imide
positions and O-propargyl group at the bay position in both
chemodosimeters greatly affected their solubility in aqueous
medium. So, firstly we studied the effect of organic solvents on
the optical properties of PS-PDI. The PS-PDI shows almost
identical absorption maxima (±5 nm) in the different polarity
solvents and similarly, no significant change in the emission
maxima (±5 nm) were observed. Moreover, no deviation was
observed in Frank-Codon factor (A0-0/A0-1 = 1.4-1.5)1 with
change in polarity of the solvents which indicates that PS-PDI
remains in molecularly dissolved state in these solvents (Fig.
S5, table S1, ESI).
PDI is 3x10-5 and 5x10-5 M respectively. All images are at concentration of 1x10-5
M
unless otherwise stated. T = THF; D = DMSO; H = H2O in v/v ratio.
has started but visually the PS-PDI at 1x10-5 M concentration
remained soluble (solution stable for more than one week)
(Fig. 1c-d, vial no. 5-8 and 11).
Conversely, in solution of DMSO, when fw = 50%, we
observed complete loss of fine structure in the absorption
spectrum of PS-PDI (c = 1x10-5 M). The maxima at 543 nm got
blue shifted at 510-520 nm and new broad absorption maxima
at 574 nm was observed (Fig. 1b). The emission maxima of PS-
PDI at 574 nm in DMSO got quenched at fw = 30-60%, followed
The optical properties of PS-PDI in the mixed organic-
aqueous solvents such as THF:H2O and DMSO:H2O were also
recorded. We observed that upon increasing fraction of water
by appearance of red shifted emission band at 630 nm (fw
=
70-90%) which indicate the transformation of monomeric PDI
molecule to aggregated form due to π-π stacking (Fig. S6b,
ESI). Impressively, 1x10-5, 3x10-5 and 5x10-5 M solution of PS-
PDI in DMSO:H2O (1:9) remained soluble and stable for at least
3 days without visual precipitation (Fig. 1d, vial no. 12-15).
The absorption spectrum of DPS-PDI exhibit fine structure
up to 60% H2O:THF and 10% H2O:DMSO mixture, however at
fw = 90% in both cases, we observed blue shifted band at ~506
and ~480 nm. Similarly, DPS-PDI shows emission at 574 and
585 nm in 60% H2O:THF and 20% H2O:DMSO mixture,
respectively, which got red shifted to 630 nm in 90% H2O:THF
or H2O:DMSO mixture (Fig. S7, ESI).
(
fw = 60%, v/v) in THF, PS-PDI (1x10-5 M) shows the presence of
sharp signature peaks around 450-550 nm in the absorption
spectrum and intensity remained unperturbed (A0-0/A0-1 ≈ 1.4).
However, at fw = >60%, hypochromic effect on absorption
maxima at 543 nm along with broadening of spectrum around
600-750 nm due to Mie scattering was observed (Fig. 1a). The
fluorescence spectrum of PS-PDI (c = 1x10-5 M) in THF showed
high emission intensity at 564 nm along with shoulder band at
600 nm. At fw = 60%, the emission maximum was red-shifted
to 570 nm along with hypochromic effect and a shoulder band
appeared at 608 nm. Whereas at fw = 90%, the emission
maxima at 570 nm, which corresponds to molecularly
dissolved state, disappeared and shoulder band at 608 nm red
shifted to 614 nm indicating the aggregation of PS-PDI (Fig.
S6a, ESI). Although at fw = 70% or 90% in THF, the aggregation
The optical properties of PDI
5
were also recorded in these
has less solubility in
solvents. However, we observed that PDI
5
comparison to PS-PDI (Fig. 1c-d, vial no. 1-4, 9-10). PDI
shows absorption maxima at 540 nm in THF or DMSO. At fw
5
=
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60% in THF, the absorption intensity gradually decreased and The presence of such internal voids represent feature
further addition of water results in precipitation whereas in reminiscent of vesicle structure and reason for such voids
10% H2O:DMSO PDI
increase in water fraction leads to blue shift at 492 nm (A0-0/A0- molecules which help PDI (hydrophobic) part to arrange in
= 0.5). The PDI remained emissive up to 50% H2O:THF and vesicle structure. Similarly, transmission electron microscopic
5 shows fine structure and further could be attributed to presence of hydrophilic (water)
5
1
20% H2O:DMSO mixture. At fw = 90% in both solvents the (TEM) images further corroborated the nanospherical
emission maxima got red shifted to 630 nm (Fig. S8, ESI). We structure of PS-PDI in THF:H2O (1:1) (Fig. 2c) (Fig. S10, ESI).
have also carried out pH titration of the PS-PDI to determine
On the other hand, the SEM images of thin films of PS-PDI
the compatibility of PS-PDI for cellular applications. The optical deposited from DMSO:H2O (1:9) solution reveal circular ‘Hair-
properties of PS-PDI remained stable over a wide pH range of brush’ like pattern where small nanorods-like structure are
2.5 to 12 (Fig. S9, ESI). So, probe PS-PDI shows good water protruding out in 3D fashion with diameter of nanorods in the
solubility in mixed organic-aqueous solvent.
range of 300-500 nm (Fig. 2e). Very few larger aggregates of
size 700 nm were also observed. As shown in figure 2e small
nanospheres or rods fused together to form long nanorods
Dynamic light scattering and microscopic studies
To support the aggregation of PS-PDI in mixed organic- whose length extended up to >1 µm and thus results are in
aqueous solvents, we have also carried out dynamic light consonance with DLS experiments. Similarly, TEM images of
scattering (DLS) experiments of PS-PDI in THF:H2O (1:1) and PS-PDI recorded in DMSO:H2O (1:9) reveal rod-like assembly
DMSO:H2O (1:9) solution. The DLS analysis of PS-PDI (1x10-5 M) on the Cu grid (Fig. 2f). The presence of few diffraction spots in
in THF:H2O (1:1) solution revealed the formation of aggregates the selected area electron diffraction (SAED) pattern in high
with diameter in the range of 300-500 nm (Fig. 2a), whereas resolution TEM (HRTEM) confirmed partial crystalline nature of
PS-PDI undergoes aggregation in DMSO:H2O (1:9) to form rod-like assembly (Fig. 2f, Inset) (Fig. S11, ESI).
larger aggregates with diameter in the range of 800-1100 nm
(Fig. 2d) and thus truly support the aggregation of PS-PDI as undergo depropargylation to produce PDI-OH (PDI-O-Na+)
observed through photophysical measurements. species and thus would result in segregation of PDI molecule
We anticipate that PS-PDI in the presence of Pd0, would
To decipher the solvent effect, the self-assembly of PS-PDI from aggregated structure due to electrostatic repulsions. So,
in THF:H2O (1:1) and DMSO:H2O (1:9) have been investigated the mechanism or interaction of PS-PDI with Pd0 was also
using microscopic techniques. The scanning electron explored with DLS experiments. From particle size analysis, we
microscopic (SEM) images of thin film on TLC plate prepared observed that the size of the PS-PDI aggregate decreases to
by drop cast technique from solution of PS-PDI in THF:H2O <10 nm on interaction with Pd0 in both THF:H2O (1:1) (Fig. 3a)
(1:1) shows nanosphere morphology with diameter in the and DMSO:H2O (1:9) (Fig. 3d) mixtures.
range of 300-500 nm in consonance with DLS experiment (Fig.
The micrographs of PS-PDI+Pd0 mixture in THF:H2O (1:1)
2b). We also observe that many of the nanospheres have an shows decrease in the size of the nanosphere (Fig. 3b,c) with
open hole on the surface and the diameter of this hole is in the average diameter in the range of 100-200 nm, with minimum
range of 20-25 nm (Fig. 2b, Inset).
size of 70 nm which we have found on the SEM and TEM data.
Fig. 2 (a) DLS analysis of PS-PDI (1x10-5 M) in THF:H2O (1:1) solution; (b/c) SEM/TEM
images for self-assembled nanospheres of PS-PDI (1x10-5 M in THF:H2O, 1:1); arrows in
image b indicate the presence of open hole on the surface of nanosphere (Inset b/c:
image of single nanosphere); (d) DLS analysis of PS-PDI (1x10-5 M) in DMSO:H2O (1:9)
solution; (e/f) SEM/TEM images for self-assembled nanorods of PS-PDI (1x10-5 M) in
DMSO:H2O, (1:9).
Fig. 3 (a) DLS analysis of PS-PDI (1x10-5 M) upon the addition of Pd0 in THF:H2O (1:1)
solution; (b/c) SEM/TEM images of morphological changes in self-assembled PS-PDI on
addition of Pd0 in THF:H2O (1:1) solution; (d) DLS analysis of PS-PDI (1x10-5 M) upon the
addition of Pd0 in DMSO:H2O (1:9) solution; (e/f) SEM/TEM images of morphological
changes in self-assembled PS-PDI on addition of Pd0 in DMSO:H2O (1:9) solution.
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We also observed complete loss of nanorods assembly with
addition of Pd0 in DMSO:H2O (1:9) and instead we observed
formation of smaller size spherical aggregates with diameter of
<200 nm (Fig. 3e). Similarly, in the TEM data, we have found
that size of the nanosphere/rods dramatically reduces in
DMSO:H2O (1:9) (Fig. 3f) in consonance with DLS studies.
Moreover, the nanospheres of PS-PDI itself and spherical
structure observed for PS-PDI+Pd0 mixture in both THF:H2O
(1:1) and DMSO:H2O (1:9) show amorphous nature because no
diffraction pattern was observed in SAED recorded in HRTEM
(Fig. S12-13, ESI).
Palladium detection with PS-PDI aggregates
The absorption spectrum of PS-PDI (c = 1x10-5 M) in HEPES
buffer-THF (1:1, v/v, pH 7.3) solution, where it exist in partial
aggregated form, exhibits maxima at 543 nm and on excitation
at 490 nm, it shows emission maxima at 564 nm. The UV-Vis
titration of PS-PDI on addition of Pd(PPh3)4, as a source of Pd0,
showed gradual decrease in the absorbance at 543 nm with
concomitant appearance of new band in the NIR region at 710
nm due to ICT process and then attained plateau after
reaching its limiting value at 3x10-5 M concentration of Pd0
(Fig. 4a). The ratiometric plot of A710/A543 vs Pd0 concentration
shows two linear increases between 10-6 - 9x10-6 M and 9x10-6
– 2x10-5 M of Pd0, followed by non-linear behavior up to 3x10-5
M. The detection limit of PS-PDI for Pd0 was found to be
1.2x10-7 M (3σ/slope).38 The visually detectable colour change
of the solution of PS-PDI from pink to colourless was observed.
The isosbestic point was observed at 560 nm.
Fig.
4
(a) UV-Vis absorption, (b) fluorescence spectra of PS-PDI (1x10-5 M) after
incremental addition of Pd0 recorded in HEPES buffer-THF (1:1, v/v, pH 7.3); Inset (a):
ratiometric plot of A710/A543 vs conc. of Pd0; Inset (b): calibration curve for determining
the lowest limit of detection; All spectra were recorded after time interval of 1 hour.
Similarly, the fluorescent titration of PS-PDI shows that on
addition of Pd0, the emission band at 564 nm gradually
decreases due to PET process and then it achieves the plateau
at 4x10-5 M concentration of Pd0 (Fig. 4b). In this process, the
purple to light brown on addition of Pd0 (3x10-5 M). All these
spectroscopic changes in PS-PDI (c
=
1x10-5 M, HEPES
buffer:DMSO (9:1, v/v) were observed within a couple of
minutes of addition of Pd0 (direct titration) in comparison to
one hour time interval in HEPES buffer:THF (1:1, v/v) solvent
system. The increase in sensitivity and fast response of PS-PDI
in DMSO:H2O (1:9, v/v) can be attributed to aggregation
because as the Pd0 interact with aggregates of PS-PDI, Pd0
finds several PS-PDI molecules in its close vicinity in
comparison to interaction of Pd0 with PS-PDI in molecularly
dissolved state. Interestingly, the optical properties of PS-PDI
in the presence of other metal ions such as Zn2+, Ni2+, Hg2+, Li+,
K+, Cs+, Ba2+, Co2+, Ca2+, Mg2+, Pb2+, Sr2+, Fe2+, Cu2+, Pd2+ (1x10-3
M) remained unchanged.
fluorescence quantum yield39 decreased from 0.8 (for PS-PDI
)
to 0.26 (PS-PDI+Pd0 mixture). The Stern-Volmer plot follows
the linear relation between the concentration ranges of 1x10-6
– 2.5x10-5 M. The Stern-Volmer constant value (Ksv) is 1x105
M−1. The minimum detection limit of Pd0 was found to be
2.1x10-8 M (3σ/slope) (Fig. 4b, Inset).
The absorption spectrum of PS-PDI in HEPES buffer:DMSO
(9:1 v/v, pH 7.3), where it exist in highly aggregated form,
shows λmax at 510 nm. On gradual addition of Pd0 solution to
the solution of PS-PDI (c = 1x10-5 M), we observed that PS-PDI
produce a new broad band with λmax at 700 nm, attributed to
the ICT, which attained a plateau at 3x10-5 M concentration of
Pd0 (Fig. S14, ESI). Similarly, weak fluorescence of PS-PDI in
HEPES buffer:DMSO (9:1 v/v, pH 7.3) solution at 630 nm
undergoes fluorescence quenching on addition of Pd0 and
attained a plateau at 3x10-5 M concentration of Pd0 (Fig. S15,
ESI). The detection limit of PS-PDI for Pd0 was found to be
We have also carried out optical titration of DPS-PDI (c =
1x10-5 M) in the presence of Pd0. On gradual addition of Pd0,
DPS-PDI (HEPES buffer-THF, 1:1, v/v, pH 7.3) showed gradual
decrease in the absorbance at 550 nm with concomitant
appearance of new band at 630 nm and then attained plateau
after reaching its limiting value at 2x10-5 M concentration of
Pd0. We also observed that absorbance intensity at 550 nm
shows only 25% decrease in comparison to 80% decrease in
6.6x10-9 M (3σ/slope), which is
~30 times lower in comparison
to THF:H2O (1:1). PS-PDI, shows visible colour change from
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case of PS-PDI. Visually detectable colour change of the Then PS-PDI treated (1x10-5 M for 30 min) HeLa cells were
solution of DPS-PDI from pink to violet, on addition of Pd0 was washed with PBS buffer (pH = 7.4, 2 times) supplemented with
observed. On the other hand, the emission band of DPS-PDI at 10% DMSO. Subsequently, 1x10-5 M, 2x10-5 M, 3x10-5 M and
580 nm gradually decreases as the concentration of Pd0 is 4x10-5 M Pd0 was added and HeLa cells were further incubated
increased and then it achieves the plateau at 2x10-5
concentration of Pd0 (Fig. S16, ESI)
M
for 4h at 37oC before imaging. We observed that fluorescence
intensity of PS-PDI inside the HeLa cells was significantly
quenched in
a concentration dependent manner and,
Imaging of Pd0 in Hela Cells using PS-PDI aggregates
intracellular fluorescence intensity vanished almost completely
Before performing the cell imaging studies, cytotoxicity of PS- at 4x10-5 M concentration of PS-PDI (Fig. 5e-f).
PDI on HeLa cells using 3-(4,5-dimethyl-2-thiazolyl)-2,5-
Kinetic Profile of PS-PDI aggregates
diphenyl-2H-tetrazolium bromide (MTT) assay was checked.
Very low cytotoxic effect on the proliferation of the HeLa cells The investigation of time dependent and concentration
was observed in the presence of different concentrations such dependent kinetic profiles of PS-PDI revealed rapid response
as 5x10-6 M, 1x10-5 M and 2x10-5 M of PS-PDI (cell viability to Pd0 with good correlation. For kinetic experiments the
92.6%, 90.5% and 88% respectively) (Fig. S17, ESI). These data absorption and emission spectrum of PS-PDI in presence of
indicates that PS-PDI (c = 1x10-5 M) can be considered to have different concentrations of Pd0 were recorded after regular
low cytotoxicity to HeLa cells and did not significantly affect time intervals in DMSO:H2O (1:9) and THF:H2O (1:1).
the cell viability.
To test the cell-internalization ability of PS-PDI and its it exists in aggregated state, when treated with 5x10-6
Impressively, PS-PDI (c = 1x10-5 M) in DMSO:H2O (1:9), where
M
response towards Pd0, HeLa cells were used. Brightfield image concentration of Pd0, we observed that within 11 min of
showed that the HeLa cells were healthy and viable response time, the emission intensity at 630 nm reached its
throughout the experiment (Fig. 5a). HeLa cells, themselves limiting value. The rate constant40 for Pd triggered
(without PS-PDI) and after incubation with Pd0 (4x10-5 M), did depropargylation reaction of PS-PDI was found to be
not exhibit any fluorescence (Fig. 5b-c). However, when HeLa x 2.303 = 0.16 s-1. Moreover, PS-PDI required only 7 and 4 min
cells were imaged after incubation with PS-PDI for 30 min at for depropargylation in the presence of 1x10-5 M and 2x10-5
K = slope
M
37°C, it showed bright red fluorescence in the cytoplasmic concentration of Pd0 with rate constant of 0.23 s-1 and 0.4 s-1,
region (λex = 488) (Fig. 5d). This depicted that PS-PDI is respectively. On the other hand, when PS-PDI was treated with
permeable to HeLa cells and can be used for bioimaging of Pd0 5x10-6 M and 2x10-5 M concentration of Pd0, the absorbance at
in the live cells.
700 nm increased and reached its limiting value within 16 min
(K = 0.15 s-1) and 12 min (0.21 s-1), respectively (Fig. S18-19,
ESI).
PS-PDI (c = 1x10-5 M) in THF:H2O (1:1) when treated with
8x10-5 M concentration of Pd0, we observed that the emission
at 564 nm dramatically decreased and reached its limiting
value within 6 min (Figure 6b). The rate constant calculated
from the plot of emission at 564 nm versus time found to be
0.148 s-1 within first 0-3 min and then rate slows down in the
next 3-6 min (0.036 s-1) before it achieves the plateau. The
depropargylation reaction of PS-PDI with 6x10-5 M and 4x10-5
M concentration of Pd0 completed in 10 min and 16 min,
respectively with rate constant value found to be 0.143 s-1 and
0.06 s-1. Similarly, PS-PDI when treated with 8x10-5
M
concentration of Pd0, we observed that within 10 min of
response time, the absorbance at 710 nm dramatically
increased to its limiting value (Fig. 6a). The rate constant was
found to be
K
= slope x 2.303 = 0.136 s-1. We also observed
that PS-PDI required 24 min (K = 0.03 s-1) and 60 min (K =
0.027 s-1) for completion of depropargylation reaction at 6x10-5
M and 4x10-5 M concentrations of Pd0, respectively (Fig. 6a-b
Inset and Fig. S20-21, ESI). From these kinetic profiles, we
Fig. 5 Confocal microscopic images of HeLa cells: (a) brightfield image of HeLa cells (b)
fluorescence image of HeLa cells without PS-PDI; (c) fluorescence image of HeLa cells
incubated with Pd0 (4x10-5 M) for 4 hours; (d) fluorescence image of HeLa cells
incubated with PS-PDI (1x10-5 M) for 30 min; (e) fluorescence image of HeLa cells
incubated with PS-PDI (1x10-5 M) for 30 min followed by incubation with Pd0 (2x10-5 M)
for four hours and (f) fluorescence image of HeLa cells incubated with PS-PDI (1x10-5 conclude that PS-PDI responds to Pd0 much faster (
~5-8 times)
M) for 30 min and then incubated with Pd0 (4x10-5 M) for four hours. The fluorescence
when present in aggregated form in comparison to their
molecularly dissolved form.
images were acquired using excitation at 488 nm.
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Fig. 7 (a) UV-Vis absorption spectra of PS-PDI in the presence of Pd0 and Pd2+ showing
applicability of PS-PDI as general Pd sensor system; (Inset) Bar graph showing A = PS-
PDI, B = PS-PDI +Pd0, C = PS-PDI +Pd2++NaBH4-PPh3, D = PS-PDI +Pd2+; (b) UV-Vis
absorption spectra of PS-PDI with Pd0 in the presence and absence of drug; (Inset) Bar
graph showing (I) = PS-PDI, (II) = PS-PDI +Pd0 (4x10-5 M), (III) = PS-PDI + Pd0 (6x10-5 M),
(IV) = PS-PDI + Pd0 (1x10-5 M).
Application of PS-PDI aggregates for Analysis of Pd in
pharmaceutical, environmental and urine samples
To check the suitability of our PS-PDI for sensing of Pd0 in the
pharmaceutical drug, we prepared various samples of PS-PDI
that contained different concentrations of Pd0 with and
without drug (disprin tablet) in HEPES buffer-THF (1:1, v/v) (pH
7.3). Interestingly, we observed that the absorption intensity
of PS-PDI solution at respective concentrations of Pd0 (0, 4x10-
6, 6x10-6 and 1x10-5 M) at 710 nm were nearly same (<10%) in
the absence and presence of drug (Fig. 7b) and thus
demonstrate the utility of PS-PDI for determining the Pd0 in
pharmaceutical sample.
Fig. 6 (a) UV-Vis absorption (b) emission spectra of PS-PDI (1x10-5 M) after addition of
Pd0 (8x10-5 M) in HEPES buffer-THF (1:1, v/v, pH 7.3) recorded after every 2 minutes for
absorption and 1 minute for emission; Time dependent and concentration dependent
kinetic profiles for PS-PDI (1x10-5 M) at λabs = 710 nm (Inset a) and at λem = 564 nm
(Inset b) after addition of 4x10-5 M, 6x10-5 M and 8x10-5 M of Pd0 recorded in HEPES
buffer-THF (1:1, v/v, pH 7.3).
PS-PDI could also be used for detection of unknown
concentration of Pd2+ in human urine sample using calibration
curve. To a solution of PS-PDI (1x10-5 M) in HEPES buffer-THF
(1:1, v/v, pH = 7.3), 350 µL each of NaBH4 and PPh3 was added
followed by addition of 100 µL of urine sample (1 mL urine
diluted to 100 mL with H2O) in separate flask. The Pd2+
concentration in adult urine sample was found to be 0.18 µg/l
(Fig. 8).
PS-PDI aggregates as general Pd sensor
Pd2+ is generally known to be the most toxic metal ion among
Pd0, Pd2+ and Pd4+ ions that exist under physiological
conditions. Since Pd2+ can be easily reduced to Pd0, our PS-PDI
could be utilized for sensing of Pd2+ in the presence of NaBH4-
PPh3 conditions. The UV-Vis spectrum of PS-PDI in HEPES
buffer-THF (1:1 v/v, pH 7.3), or HEPES buffer-DMSO (9:1 v/v,
pH 7.3) and NaBH4-PPh3 (350 µL each of 10 mM solution) on
gradual addition of PdCl2, showed gradual decrease in the
absorption band at 543 nm with concomitant appearance of
new red shifted band at 710 nm with isosbestic point at 560
nm. The ratiometric behaviour (A710/A543) of PS-PDI shows
good correlation up to 2x10-5 M Pd2+ ions. Similarly, the
fluorescence spectrum of PS-PDI underwent fluorescence
quenching in the presence of Pd2+ at 564 nm (Fig. S22, ESI). We
also performed UV-Vis experiments of PS-PDI (c = 1x10-5 M) in
the presence of 2x10-5 M Pd0 or Pd2+ (with or without NaBH4-
PPh3) and observed that both samples exhibit similar intensity
for 710 nm absorption band whereas Pd2+ without NaBH4-PPh3
did not convert PS-PDI to PDI-OH and thus support our
hypothesis for application of PS-PDI as general Pd sensor
system (Fig. 7a).
Fig. 8 UV-Vis absorption spectrum of PS-PDI (1x10-5 M) and PS-PDI + urine showing the
capability of PS-PDI for sensing of Pd2+ in urine sample; U = urine sample; R = reducing
agent (NaBH4-PPh3); Inset: calibration curve for determining the unknown
concentration of Pd2+ in urine sample.
8 | J. Name., 2012, 00, 1-3
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We also carried out analysis of Pd0 in complicated
environmental samples such as tap water, pond water and
industrial waste water collected from different sources. The
different samples were spiked with various concentrations of
Pd0 ions. The concentration thus, determined by absorbance
spectroscopy agreed with actual concentration with a relative
error of 1.9% or better and a RSD below 3.9% (tap water);
relative error of 1.2% or better and a RSD below 2.0% or
better (pond water) and relative error of 1.7% or better and a
RSD below 4.3% or better (industrial waste water) (Table 1).
Scheme 3. The proposed mechanism for the depropargylation reaction of PS-PDI in the
Moreover, The concentration thus, determined by presence of Pd0 and Pd2+ (with reducing agents).
fluorescence spectroscopy agree with actual concentration
with a relative error of 1.3% or better and a RSD below 2.7%
(tap water); relative error of 2.3% or better and a RSD below
2.6% or better (pond water) and relative error of 0.9% or
better and a RSD below 1.8% or better (industrial waste water)
(Table 1 and Table S2).
Competitive experiments
To ascertain the selectivity of PS-PDI for Pd0, the UV-Vis and
emission spectrum of PS-PDI were also recorded in the
presence of other probable interfering metal ions. We
observed that only addition of Pd0 results in increase of
absorbance at 710 nm whereas, on addition of other metal
ions no change in the absorption spectrum was observed.
Similarly, the fluorescence intensity of PS-PDI at 564 nm got
quenched on addition of Pd0, whereas no significant quenching
of fluorescence intensity was observed in the presence of
other metal ions. Moreover, solutions of PS-PDI (1x10-5 M),
one of the probable interfering metal ions (1x10-4 M) and Pd0
(2x10-5 M) were prepared and their absorption and emission
spectra were recorded. The absorption and emission intensity
of PS-PDI-Pd0 mixture and PS-PDI-Pd0-Mn+ solution remained
unperturbed and thus points out that presence of other
probable interfering metal ions does not interfere in the
detection of Pd0 (Fig. S24, ESI).
Chemodosimeter mechanism
The cause of change in colour or fluorescence intensity of the
solution of PS-PDI on addition of Pd0 could be attributed to de-
propargylation to provide PDI-OH parallel to the earlier
reported literature (scheme 3).41 For proving this mechanism,
PDI-OH was synthesized by earlier reported procedure42 and
its UV-Vis spectrum was recorded in HEPES buffer-THF (1:1,
v/v, pH 7.3). It exhibits two absorption maxima at 543 and 710
nm and a weak fluorescence at 564 nm in the emission
spectrum. In the pH titration of PDI-OH in THF:H2O (1:1, v/v)
we observed decrease in the intensity of absorption band at
543 nm whereas absorption intensity increased at 710 nm with
change in the pH of the solution from 6.0 to 11.0 (Fig. S23,
ESI).
Conclusion
Table 1. Application of PS-PDI for the determination of Pd0 in the various
environmental samples (tap water, pond water and industrial waste water)
PS-PDI shows aggregation in mixed organic-aqueous solvents
with formation of self-assembled nanovesicles in THF:H2O (1:1)
and nanorod-like structures in DMSO:H2O (1:9) as evidenced
by DLS, SEM and TEM studies. The aggregates of PS-PDI
respond to Pd0 via de-aggregation or dis-assembly of
nanovesicles/rods morphology. In solution form, PS-PDI
aggregates gives new red-shifted absorption maxima in the
NIR region at 710 nm (ratiometric) and quenching of its
emission intensity at 630 nm or 564 nm in the presence of Pd0
and Pd2+ (with reducing reagents) in aqueous buffer and could
be useful as general Pd0/Pd2+ chemodosimeter. Pd0 mediated
depropargylation of the PS-PDI to the PDI-OH has been
assigned as the cause of observed photophysical changes in
the presence of Pd0. PS-PDI was successfully applied for the
detection of Pd0 in environmental and drug samples and Pd2+
in urine sample. Moreover, PS-PDI could be easily internalized
Sample
Added
(µM)
Conc. SDa (µM)
(relative error)
Added
(µM)
Conc. SDa (µM)
/ (relative error)
/
(UV @710 nm)
(FI @564 nm)
Tap
Water
5.0
5.0 0.08 (1.10)
10.0 0.19 (1.31)
25.0 0.55 (1.55)
15.0 0.12 (0.53)
20.0 0.15 (0.58)
25.0 0.23 (0.70)
5.0 0.12 (1.64)
10.0 0.11 (0.77)
25.0 0.76 (2.17)
10.0
15.0
20.0
5.0
10.0 0.04 (0.31)
15.0 0.05 (0.26)
20.0 0.24 (0.69)
5.0 0.01 (0.19)
15.0 0.27 (1.37)
25.0 0.33 (1.02)
5.0 0.05 (0.66)
15.0 0.11 (0.38)
20.0 0.06 (0.16)
10.0
25.0
15.0
20.0
25.0
5.0
Pond
Water
15.0
25.0
5.0
Industrial
Waste water
10.0
25.0
15.0
20.0
into HeLa cells with low cytotoxicity and could detect 2x10-5
4x10-5 M of Pd0 in live HeLa cells.
–
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13. a) M. A. Kaloo, R. Mishra, J. Sankar, J. Mater. Chem. C 2015
1640-1644; b) H.-R. Cheng, Y. Qian, Sensors Actuators Chem. B
2015 219, 57-64.
14. a) B. Roy, T. Noguchi, D. Yoshihara, Y. Tsuchiya, A. Dawn, S.
Shinkai, Org. Biomol. Chem. 2014 12, 561-565; b) Y. Wang, L.
Zhang, G. Zhang, Y. Wu, S. Wu, J. Yu, L. Wang, Tetrahedron Lett.
2014 55, 3218-3222.
15. a) K. Liu, Z. Xu, M. Yin, W. Yang, B. He, W. Wei, J. J. Shen, J.
Mater. Chem. B 2014 2093-2096; b) A. K. Dwivedi, M.
Pandeeswar, T. Govindaraju, ACS Appl. Mater. Interfaces 2014
21369-21379.
16. J. Li, Y. Wu, F. Song, G. Wei, Y. Cheng, C. J. Zhu, J. Mater. Chem.
2012 22 , 478-482.
, 3,
Acknowledgements
This work was supported by the CSIR (02(0084)/12/EMR-II) and
DST-SERB fast track grant (CS/2012/088). We thank UGC for
CAS status to the department, UPE programme and DST for
FIST programme. LSM and KK are thankful to UGC for SRF and
DST-SERB for JRF fellowship, respectively. Live cell experiments
were supported by a grant from DBT, India (BT/IN/German
/13/VK/2010) to VV.
,
,
,
,
2,
, 6,
Notes and references
1. a) F. Wurthner, Chem. Commun. 2004, 1564-1579; b) F. Wurthner,
,
C. R. Saha-Moller, B. Fimmel, S. Ogi, P. Leowanawat, D.
17. L. Zhang, Y. Wang, J. Yu, G. Zhang, X. Cai, Y. Wu, L. Wang,
Tetrahedron Lett. 2013, 54, 4019-4022.
Schmidt, Chem. Rev.
Heterocycles 1995 40, 477-500.
2. a) C. Huang, S. Barlow, S. R. Marder, J. Org. Chem. 2011
,
2015, 115, 11967-11998; c) H. Langhals
,
,
18. a) X. Feng, Y. An, Z. Yao, C. Li, G. Shi, ACS Appl. Mater.
,
76, 2386-
Interfaces 2012, 4, 614-618; b) B. Wang, F. Wang, H. Jiao, X. Yang
2407; b) X. Guo, A. Facchetti, T. J. Marks, Chem. Rev. 2014, 114,
C. Yu, Analyst 2010, 135, 1986-1991.
8943-9021
19. a) X. Lu, W. Zhu, Y. Xie, X. Li, Y. Gao, F. Li, H. Tian, H., Chem.
3. a) C. Li, H. Wonneberger, Adv. Mater. 2012
Zhan, A. Facchetti, S. Barlow, T. J. Marks, M. A. Ratner, M. R.
Wasielewski, S. R. Marder, Adv. Mater. 2011 23, 268-284.
4. a) Q. L. Zhao, S. Zhang, Y. Liu, J. Mei, S. J. Chen, P. Lu, A. J. Qin,
Y. G. Ma, J. Z. Sun, B. Z. Tang, J. Mater. Chem. 2012 22, 7387-
7394; b) R. C. Liu, M. W. Holman, L. Zang, D. M. Adams, J. Phys.
Chem. A 2003 107, 6522-6526.
, 24, 613-636; b) X. W.
Eur. J. 2010
Ku, D.H. Qu, C.P. Chang, H. Tian, Dyes Pigm. 2005
20. X. He, H. Liu, Y. Li, S. Wang, Y. Li, N. Wang, J. Xiao, X. Xu, D.
Zhu, Adv Mater. 2005 17, 2811-2815.
21. a) L. Chunli, Z. Haiyan, L. Xiaotian, Z. Weiguang, H. Yongwei, J.
Mater.Chem.C 2015, 2778-2782; (b) H. Yongwei, Z. Weiguang, Z.
Haiyan, L. Chunli, J. Mater. Chem. C 2015 , 466-472.
22. C. Backes, C. D. Schmidt, F. Hauke, C. Bottcher, J. Am. Chem. Soc.
2009 131, 2172-2184.
23. a) L. Zhang, Y. K. Che, J. S. Moore, Acc. Chem. Res. 2008
1608; b) D. Gorl, X. Zhang, F. Wurthner, Angew. Chem., Int. Ed.
2012 51, 6328-6348.
24. a) Z. J. Chen, V. Stepanenko, V. Dehm, P. Prins, L. D. A. Siebbeles,
J. Seibt, P. Marquetand, V. Engel, F. Wurthner, Chem. –Eur. J. 2007
13, 436-449; b) F. Fennel, S. Wolter, Z. Q. Xie, P. A. Plotz, O. Kuhn,
F. Wurthner, S. Lochbrunner, J. Am. Soc. Chem. 2013 135, 18722-
18725; c) M. A. Muth, G. Gupta, A. Wicklein, M. C. Orozco, T. T.
Albrecht, M. Thelakkat, J. Phys. Chem. C 2014 118, 92-102.
25. a) Y. Sun, C. He, K. Sun, Y. Li, H. L. Dong, Z. H. Wang, Z. B. Li,
Langmuir 2011 27, 11364-11371; b) W. Su, Y. X. Zhang, C. T.
Zhao, X. Y. Li, J. Z. Jiang, ChemPhysChem 2007 , 1857-1862; c)
,
16, 8355-8364; b) J. Ren, X.L. Zhao, Q.C. Wang, C.F.
,
64, 193-200.
,
,
,
3
,
,
,
3
5. A. Wicklein, S. Ghosh, M. Sommer, F. Wurthner, M. Thelakkat, ACS
Nano 2009, 3, 1107-1114.
,
6. a) Y. Li, T. Liu, H. Liu, M.Z. Tian, Y. Li, Acc. Chem. Res. 2014
1186-1198; b) W. Herbst, K. Hunger, Industrial Organic Pigments,
VCH -Weinheim, (3rd Ed.) 2004
7. a) H. Langhals, Helv. Chim. Acta 2005
Ahrens, Chem. Mater. 2003 15, 2684-2686.
8. a) J. E. Anthony, Chem. Mater. 2011 23, 583-590; b) A. Ringk, X.
, 47,
,
41, 1596-
.
,
,
88, 1309-1343; b) M. J.
,
,
,
R. Li, F. Gholamrezaie, E. C. P Smits, A. Neuhold, Moser, C. V. D.
,
Marel, G. H. Gelinck, R. Resel, D. M. D. Leeuw, P. Strohriegl, Adv.
Funct. Mater. 2013, 23, 2016-2023.
,
9. M. Thelakkat, P. Posch, H.-W. Schmidt, Macromolecules 2001
,
34
,
,
7441-7447.
,
10. a) P. Singh, K. Kumar, G. Bhargava, S. Kumar, J. Mater. Chem. C
2016
G. Bhargava, A. Walia, S. Kumar, Chem. Commun. 2014
,
8
,
4
, 2488-2497; (b) P. Singh, L. S. Mittal, V. Vanita, R. Kumar,
50, 13994-
X. Q. Li, X. Zhang, S. Ghosh, F. Wurthner, Chem.-Eur. J. 2008, 14,
,
8074-8078.
13997; c) P. Singh, L. S. Mittal, S. Kumar, G. Bhargava, S. Kumar,
26. a) Z. G. Zhang, C. L. Zhan, X. Zhang, S. L. Zhang, J. H. Huang, A.
D. Q. Li, J, N, Yao, Chem.-Eur. J. 2012 18, 12305-12313; b) J.
Zhou, L. Xue, Y. Shi, X. Y. Li, Q. B. Xue, S. Q. Wang, Langmuir
2012 28, 14386-14394; c) Y. W. Huang, L. N. Fu, W. J. Zou, F. L.
Zhang, Z. X. Wei, J. Phys. Chem. C 2011 115, 10399-10404.
27. a) S. Sandhu, R. Kumar, P. Singh, A. Mahajan, M. Kaur, S. Kumar,
ACS Appl. Mater. Interfaces 2015 , 10491-10500; b) S. Kumar, P.
Singh, A. Mahajan, S. Kumar, Org. Lett. 2013 15, 3400-3403;
28. a) K. B Joshi, P. Singh, Tetrahedron Lett. 2014 55, 3534-3537; b) K.
J. Fluoresc. 2014, 909-915; d) M. Marcia, P. Singh, F. Hauke, M.
,
Maggini, A. Hirsch, Org. Biomol. Chem. 2014
11. a) A. Weißenstein, F. Wurthner, Chem. Commun. 2015
3418; b) T. H. Rehm, M. R. Stojkovic, S. Rehm, M. Skugor, I.
Piantanida, F. Wurthner, Chem. Sci. 2012 , 3393-3397.
12. a) P. D. Frischmann, V. Kunz, V. Stepanenko, F. Wurthner, Chem. –
Eur. J. 2015 21, 2766-2769; b) S. Malkondu, S. Erdemir, Dyes
Pigm., 2015 113, 763-769.
,
12, 7045-7058.
,
,
51, 3415-
,
,
,
3
,
7
,
,
,
,
B. Joshi, P. Singh, S. Verma, Biofabrication 2009, 1, 025002-
025007.
10 | J. Name., 2012, 00, 1-3
This journal is © The Royal Society of Chemistry 20xx
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Page 12 of 12
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DOI: 10.1039/C6TB00512H
Journal Name
ARTICLE
29. a) P. Singh, V. Venkatesh, J. Kumar, N. Nagapradeep, S. Verma, A.
Bianco, Nanoscale 2012 , 1972-1974; b) P. Singh, F. M. Toma, J.
Kumar, V. Venkatesh, J. Raya, M. Prato, S. Verma, A. Bianco,
Chem. -Eur. J. 2011 17, 6772–6780; c) P. Singh, J. Kumar, F.M.
Toma, J. Raya, M. Prato, B. Fabre, S. Verma, A. Bianco, J. Am.
Chem. Soc. 2009 131, 13555–13562.
30. a) S. Cacchi, G. Fabrizi, Chem. Rev. 2005
Sore, R. J. Warren, D. Galloway, D. R. Spring, Chem. Soc. Rev.
2012 41, 1845-1866.
31. a) R. M. Yusop, A. Unciti-Broceta, E. M. V. Johansson, R. M.
,
4
,
,
,
105, 2873-2920; b) H. F.
,
Sanchez-Martin, M. Bradley, Nat. Chem. 2011
,
3
, 239-243; b) C. L.
S. Wiseman, F. Zereini, Sci. Total Environ. 2009
,
407, 2493-2500; c)
F. Zereini, C. Wiseman, W. Puettmann, Environ. Sci. Technol. 2007
41, 451-456.
32. a) K. Van Meel, A. Smekens, M. Behets, P. Kazandjian, R.
VanGrieken, Anal. Chem. 2007 79, 6383-6389; b) C. Locatelli, D.
Melucci, G. Torsi, Anal. Bioanal. Chem. 2005 382, 1567-1573.
,
,
,
33. a) S. Goswami, D. Sen, N. K. Das, H. K. Fun, C. K. Quah, Chem.
Commun. 2011, 9101-9103; b) X. J. Peng, H. L. Li, J. L. Fan, F. L.
Song, H. Zhu, J. J. Du, S, G. Sun, Chem.-Eur. J. 2010
12356; c) B. Zhu, C. Gao, Y. Zhao, C. Liu, Y. Li, Q. Wei, Z. Ma, B.
Du, X. Zhang, Chem. Commun. 2011 47, 8656-8658.
34. a) M.Y. Chae, A.W. Czarnik, J. Am. Chem. Soc. 1992
9705; b) K. Kaur, R. Saini, A. Kumar, V. Luxami, N. Kaur, P. Singh
and S. Kumar, Coord. Chem. Rev. 2012 256, 1992-2028.
, 16, 12349-
,
,
114, 9704-
,
35. M. P. Tracey, D. Pham, K. Koide, Chem. Soc. Rev. 2015, 44, 4769-
4791.
36. a) A. Rajasingh, R. Cohen, E. Shirman, L. J. W. Shimon, B.
Rybtchinski, J. Org. Chem. 2007 72, 5973-5979; (b) H. Langhals, O.
,
Krotz, K. Polborn, P. Mayer, Angew. Chem. Int. Ed. 2005, 44, 2427-
2428.
37. a) L. M. Wang, Z. J. Chen, G. Zou, L. Zhang, G. J. Zhang, X. F. Cai,
M. S. Teng, Dyes Pigm. 2012 94, 410-415; b) X. Kong, J. Gao, T.
,
Ma, M. Wang, A. Zhang, Z. Shi, Yanhong Wei, Dyes Pigm. 2012
,
95, 450-454
38. J. Mokac, A. M. Bond, S. Mitchell, G. Scollary, Pure Appl. Chem.
1997 69, 297-328.
39. J. N. Demas, G. A. Grosby, J. Phys. Chem. 1971
40. a) L. Yuan, W. Lin, Y. Yang, Chem. Commun. 2011
b) S. Goswami, S. Das, K. Aich, D. Sarkar, T. K. Mondal,
Tetrahedron Lett. 2014 55, 2695-2699.
41. a) M. Pal, K. Parasuraman, K. R. Yeleswarapu, Org. Lett. 2003
349-352; b) B. Liu, H. Wang, T. Wang, Y. Bao, F. Du, J. Tian, Q. Li,
R. Bai, Chem. Commun. 2012 48, 2867-2869.
42. Y. Li, H. Zheng, Y. Li, S. Wang, Z. Wu, P. Liu, Z. Gao, H. Liu, D.
Zhu, J. Org. Chem. 2007 72, 2878-2885.
,
,
75, 991-1024.
47, 6275–6277;
,
,
,
,
, 5,
,
,
This journal is © The Royal Society of Chemistry 20xx
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