Browsing by Author "Rajendra Prasad Paitandi"

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An AIE active BODIPY based fluorescent probe for selective sensing of Hg 2 + via dual mechanism PET and CHEF
(World Scientific, 2021) Vishwa Deepak Singh; Rajendra Prasad Paitandi; Yogesh Kumar; Daya Shankar Pandey
A pyrazole appended BODIPY ligand (L) is synthesized and thoroughly characterized by various spectroscopic studies (1H, 13C, 11B, 19F, ESI-MS, UV-vis and fluorescence). The ligand (L) displays aggregation induced emission (AIE) in solution (a mixture of CH3OH and water) and solid state. The vital role of the restriction of intramolecular rotation (RIR) in AIE is supported by viscosity experiments and fluorescence lifetime studies. Photophysical behaviour and aggregate morphology is investigated by UV-vis, emission and scanning electron microscopy (SEM). Multiple strong intermolecular hydrogen bonds (C-H ··· N and C-H ···F) play a significant role in the AIE response. In addition, L shows strong sensitivity toward Hg2+ion via chelation induced enhanced fluorescence (CHEF) mechanism. Job's plot analysis suggested a 1:1 binding stoichiometry between L and Hg2+, which has been further supported by electrospray ionization mass spectrometry and density functional theory. © 2021 World Scientific Publishing Company.
Anticancer Activity of Iridium(III) Complexes Based on a Pyrazole-Appended Quinoline-Based BODIPY
(American Chemical Society, 2017) Rajendra Prasad Paitandi; Sujay Mukhopadhyay; Roop Shikha Singh; Vinay Sharma; Shaikh M. Mobin; Daya Shankar Pandey
A pyrazole-appended quinoline-based 4,4-difluoro-4-bora-3a,4a-diaza-s-indacene (L1, BODIPY) has been synthesized and used as a ligand for the preparation of iridium(III) complexes [Ir(phpy)2(L1)]PF6 (1; phpy = 2-phenylpyridine) and [(η5-C5Me5)Ir(L1)Cl]PF6 (2). The ligand L1 and complexes 1 and 2 have been meticulously characterized by elemental analyses and spectral studies (IR, electrospray ionization mass spectrometry, 1H and 13C NMR, UV/vis, fluorescence) and their structures explicitly authenticated by single-crystal X-ray analyses. UV/vis, fluorescence, and circular dichroism studies showed that complexes strongly bind with calf-thymus DNA and bovine serum albumin. Molecular docking studies clearly illustrated binding through DNA minor grooves via van der Waals forces and their electrostatic interaction and occurrence in the hydrophobic cavity of protein (subdomain IIA). Cytotoxicity, morphological changes, and apoptosis have been explored by 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT) assay and Hoechst 33342 staining. IC50 values for complexes (1, 30 μM; 2, 50 μM) at 24 h toward the human cervical cancer cell line (HeLa) are as good as that of cisplatin (21.6 μM) under analogous conditions, and their ability to kill cancer cells lies in the order 1 > 2. Because of the inherent emissive nature of the BODIPY moiety, these are apt for intracellular visualization at low concentration and may find potential applications in cellular imaging and behave as a theranostic agent. © 2017 American Chemical Society.
Cationic Ru(II), Rh(III) and Ir(III) complexes containing cyclic π-perimeter and 2-aminophenyl benzimidazole ligands: Synthesis, molecular structure, DNA and protein binding, cytotoxicity and anticancer activity
(Elsevier, 2016) Amit Kumar; Ashish Kumar; Rakesh Kumar Gupta; Rajendra Prasad Paitandi; Krishna Beer Singh; Surendra Kumar Trigun; Maninder Singh Hundal; Daya Shankar Pandey
Synthesis, characterization, DNA and protein binding as well as anticancer activity of the organometallic complexes [(η6-C6H6)RuCl(APBI)]Cl (1), [(η6-p-MeC6H4Pri)RuCl(APBI)]Cl (2), [(η6-C6Me6)RuCl(APBI)]Cl (3), [(η5-C5Me5)RhCl(APBI)]Cl·H2O (4) and [(η5-C5Me5)IrCl(APBI)]Cl·H2O (5) containing 2-aminophenyl benzimidazole (APBI) have been described. The complexes 1-5 exhibited strong DNA, protein binding and anticancer activity against cervical cancer (SiHa) cell line. Their binding with calf thymus DNA (CT-DNA) and bovine serum albumin (BSA) have been examined by absorption and emission spectral studies. Strong interactions between complexes and CT-DNA have been affirmed by absorption spectral and EthBr displacement studies, while interaction with BSA via static quenching explored by fluorescence titration, synchronous and 3D fluorescence spectroscopy. The interactions between 1-5 and DNA has also been scrutinized by 1H NMR spectral studies using guanosine as a model for DNA. These results have been supported by DFT calculations and molecular docking studies. Cytotoxicity, apoptosis and in vitro anticancer activity of 1-5 toward SiHa cell line have been investigated by MTT assay and acridine (AO)/ethidium bromide (EthBr) fluorescence staining. Overall results revealed that DNA and protein binding, as well as anticancer activity of 1-5 follows the order as 5 > 3 > 2 > 1 > 4. © 2015 Elsevier B.V. All rights reserved.
Controlling Aggregation and Excited-State Intramolecular Proton Transfer in BODIPYs by Incorporation of 2-(2-Hydroxyphenyl)quinazoline and Variation of Substituents
(American Chemical Society, 2020) Bhupendra Kumar Dwivedi; Vishwa Deepak Singh; Rajendra Prasad Paitandi; Daya Shankar Pandey
A series of BODIPY-based AIEgens (QB1-QB5 and Bis-QB) containing 2-(2-hydroxyphenyl)quinazoline have been synthesized and thoroughly characterized. Photophysical properties of these compounds in solution and the aggregated state have been meticulously investigated and fine-tuned via structural modifications. These display green emission (∼530 nm) in solution and bright red emission (600-655 nm) in the aggregated/solid state with increased quantum yield. Crystal structure analyses and spectral studies revealed efficient J-type aggregation in these derivatives. Significant impact of 2-(2-hydroxyphenyl)quinazoline toward modulating intermolecular interactions and facilitating J-type stacking between BODIPY units has also been established. Moreover, the essential role of excited-state intramolecular proton transfer (ESIPT) in inducing emission in the aggregated state and tuning of ESIPT emission by variation of substituents have been supported by various studies. Copyright © 2020 American Chemical Society.
Corrigendum to ‘Recent developments in metal dipyrrin complexes: Design, synthesis, and applications’ [Coord. Chem. Rev. 414 (2020) 213269] (Coordination Chemistry Reviews (2020) 414, (S0010854519304175), (10.1016/j.ccr.2020.213269))
(Elsevier B.V., 2020) Roop Shikha Singh; Rajendra Prasad Paitandi; Rakesh Kumar Gupta; Daya Shankar Pandey
The authors regret that some of the copyright permissions were omitted from the published version of this review. The corrected figure captions are listed below. The authors apologize for this omission. Fig. 7. Examples of homoleptic complexes based on trivalent metal ions. Reprinted with permission from ref 56. Copyright @ 2006 American Chemical Society. Fig. 9. Structures of Fe(II) complexes of dipyrromethene. Reprinted with permission from ref 12. Copyright @ 2011 American Chemical Society. Fig. 10. Structure of complexes 2 (a), 3 (b) and 4 (c). Reprinted with permission from ref 11. Copyright @ 2009 American Chemical Society. Fig. 12. Chemical structure of dipyrrin 17 and Ga(III) complex 18. Reprinted with permission from ref 76. Copyright @ 2010 American Chemical Society. Fig. 18. Crystal structure of 80 and 81. Reprinted with permission from ref 77. Copyright 2009 The Royal Society of Chemistry. Fig. 22. Structure of metal complex 101. Reprinted with permission from ref 151. Copyright 2016 The Royal Society of Chemistry. Fig. 33. Zn2+ detection by dipyrromethanes 146–148. Reprinted with permission from ref 173. Copyright 2014 The Royal Society of Chemistry. Fig. 38. Complexation of 160 with Cd2+ and Hg2+ ions (a). Crystal structure of 161 (b). Reprinted with permission from ref 181. Copyright 2017 Centre National de la Recherche Scientifique (CNRS) and The Royal Society of Chemistry. Fig. 39. (a) Chemical structures of 162 and 163. Ar = t-Bu; (b) A photograph showing the color changes of 163 (25 mM) in the presence of various anions (40 equiv.) in DMSO; (c) UV–Vis spectral changes of 163 (10 μM) in the presence of F− (0–180 equiv.) in DMSO. Reprinted with permission from ref 186. Copyright 2010 The Royal Society of Chemistry. Fig. 40. (a) Chemical structures of 164–166; (b) and (c) image showing the color changes of probe 166 in the presence of different anions, (b) in CH2Cl2; (c) in DMSO–H2O. Reprinted with permission from ref 187. Copyright 2012 The Royal Society of Chemistry. Fig. 41. (a) Structures of compounds 167–169 bearing α-formyl groups; (b) photograph showing the color changes of solution of 167 in CHCl3 after addition of different anions (1.2 equiv). Reprinted with permission from ref 188. Copyright 2014 The Royal Society of Chemistry. Fig. 44. (a) ORTEP view of the metallotecton Δ-178b. (b) Showing 1-D zig-zag chains of metallotecton Δ-178b linked by hydrogen bonds involving two of the three carboxyl groups of each tecton. Reprinted with permission from ref 194. Copyright 2007 The Royal Society of Chemistry Fig. 45. Crystal structures of 179 and 180. Reprinted with permission from ref 57. Copyright 2009 The Royal Society of Chemistry. Fig. 46. Dimeric structure of dipyrrin 181 (a) and its nickel (II) complex 182 (b) as determined by X-ray crystallography. Representing a portion of the 1-D networks based on the [Formula presented] (12) connectivity pattern of 181 (c) and the distorted square planar/ tetrahedral coordination bonding motif in 182 (d). Reprinted with permission from ref 195. Copyright 2011 The Royal Society of Chemistry. Fig. 48. Showing space-filling representation of coordination polymers formed 199 (top right) and 200 (top left) and stick representation of 200 (bottom) viewed down the crystallographic c-axis, Reprinted with permission from ref 199. Copyright 2004 American Chemical Society. Fig. 49. Chemical structure of 201 (a), Molecular hexagons (b) and helical coordination polymers (c) comprising the supramolecular structure. Reprinted with permission from ref 200. Copyright © 2004 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim Fig. 50. Chemical structure of 202 (a), ORTEP view of 203 (b) and Ag–π interaction 204. Reprinted with permission from ref 201. Copyright 2007 The Royal Society of Chemistry. Fig. 51. Chemical structures of 205–209 and crystal structure of 210. Reprinted with permission from ref 202. Copyright 2004 American Chemical Society. Fig. 52. (a) Layered structure in a crystal of 209 (b) Ribbon like structure and the packing diagram in a crystal of 210. The hydrogen bonds are denoted by dotted lines. Reprinted with permission from ref 202. Copyright 2004 American Chemical Society. Fig. 54. Chemical structure of 216 (a) and 2-D network (b) formed by its complex with Cu(OAc)2. Reprinted with permission from ref 205. Copyright 2009 The Royal Society of Chemistry. Fig. 56. (a) A portion of the 1-D CP observed in the crystalline phase for 221. (b) A portion of the 1-D hydrogen bonded network in the crystal structure of 222. Reprinted with permission from ref 25. Copyright 2012 The Royal Society of Chemistry. Fig. 59. Portions of the crystal structures of CPs 231–234. Reprinted with permission from ref 207. Copyright 2014 The Royal Society of Chemistry. Fig. 60. Chemical structure of 235, portions of crystal structures of 236 and 237. Reprinted with permission from ref 209. Copyright 2007 The Royal Society of Chemistry. Fig. 69. Chemical structures of 256 and 257. Absorption spectrum of 256 in MeCN. The green area covers excitations of the iridium complex due to LC and MLCT transitions, the red shaded region covers π–π* excitations of the NDI and the blue regions covers excitations of the TAA. The absorption spectrum of 257 (violet solid line) and corresponding phosphorescence spectrum (violet line), excitation spectrum (green solid line). Reprinted with permission from ref 217. Copyright 2013 PCCP Owner Societies. Fig. 72. (a) Image of a free-standing film of 268-SWCNT (thickness of 64 μm). (b) TEM image of 268-SWCNT subjected to electron energy-loss spectroscopy (EELS) mapping. EELS mapping for: (c) carbon K edge intensity and (d) Zn M2 and M3 edge intensities. (e) Overlapped image of (b) and (c). (f) Voltage-difference/temperature difference plots for pristine SWCNTs (black) and 33-SWCNT (orange). (Reprinted with permission from ref 221. Copyright 2015 The Royal Society of Chemistry. Fig. 73. Photoelectric conversion profile using 268 as an active material. (a) Image of a thin film of 268 on a SnO2 electrode. (b) Anodic photocurrent signal after irradiation of a working electrode (SnO2 substrate modified with 268 as shown in (a) with intermittent 500 nm light. (c) Action spectrum for the photocurrent generation (orange dots) and absorption spectrum of 268 on a SnO2 substrate (gray solid line). Reprinted with permission from ref 221. Copyright 2015 The Royal Society of Chemistry. Fig. 74. Structures of dipyrromethene ligand and bis(dipyrrinato)Zn(II) complex; nanosheet 269. Reprinted with permission from ref 222. Copyright © 2015, Springer Nature. Fig. 75. (a) Anodic current response after irradiation of the working electrode (SnO2 substrate modified with 36-layer 269) with intermittent 500 nm light (0.1 M tetrabutylammonium perchlorate with 0.05 M TEOA in acetonitrile) (b) action spectrum for the photocurrent generation (magenta dots) and absorption spectrum of 269 (black solid line). (c) Changes in UV–vis spectra upon stepwise depositions of single-layer 269 on a quartz substrate. (d) Showing linear relationship between the absorbance at 500 nm and number of deposition cycles. Reprinted with permission from ref 222. Copyright © 2015, Springer Nature. Fig. 76. Left: chemical structure of porphyrin–dipyrrin hybrid ligand 271. Right: a) Typical photoelectric conversion response upon irradiation of the 270-physisorbed photoanode with intermittent 440 nm monochromatic light. b) Action spectrum for the photocurrent generation (orange dots) and absorption spectrum of 270 (green solid line). Reprinted with permission from ref 223. 2017 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim Fig. 82. (a) Chemical structure of 286 (b) UV–vis spectra showing reductive conversion of Cr(VI) to Cr(III) AuNPs (c) AuNPs@prGO500 (d) The plot of conversion vs. time as monitored by UV–vis spectroscopy (e) Schematic presentation for Cr(VI) reduction on AuNPs@prGO500. Reaction conditions: HCOOH = 0.2 mL, [Cr2O72-] = 0.2 mM and catalytic amount = 1 mg/mL (25 µL) levels (0.1 μM to 0.1 M) in 50 mM phosphate buffer solutions at pH = 4.5. Reprinted with permission from ref 233. Copyright 2016 The Royal Society of Chemistry. Fig. 84. Crystal structure of Pd(II)bis-dipyrrinato complex 293 (Reprinted with permission from ref 237. 2016 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim) and Mn(III)-bis(phenolate)dipyrrin complex 294. Fig. 85. Crystal structures of U(VI) complex 295 (a) U(IV) complex 296 (b) and Fe(III) complexes 297 (c), 298 (d) and 299 (e), Reprinted with permission from ref 239 (Copyright 2017 American Chemical Society). Scheme 14. Synthesis and crystal structure of compound 100. Reprinted with permission from ref 150. Copyright 2011 The Royal Society of Chemistry. © 2020
Cyclometalated Ir(III) Complexes Involving Functionalized Terpyridine-Based Ligands Exhibiting Aggregation-Induced Emission and Their Potential Applications in CO2 Detection
(American Chemical Society, 2018) Vishwa Deepak Singh; Rajendra Prasad Paitandi; Bhupendra Kumar Dwivedi; Roop Shikha Singh; Daya Shankar Pandey
Synthesis of three novel terpyridine-based donor-acceptor (D-A) ligands (TP1, TP2, TP3) and cyclometalated iridium complexes [Ir(ppy)2TP1]+PF6 - (C1), [Ir(ppy)2TP2]+PF6 - (C2), and [Ir(ppy)2TP3]+PF6 - (C3) [ppy = 2-phenyl pyridine] involving these were described. The ligands and complexes were characterized by spectroscopic studies (1H, 13C, 19F, 31P, ESI-MS, UV-vis, and fluorescence). Crucial role of intermolecular interactions in aggregation-caused quenching (ACQ; C2) and aggregation-induced emission (AIE; C3) was rationalized by X-ray single-crystal analyses. Vital role of restricted intramolecular rotation (RIR) in inducing AIE upon aggregation via π-π interactions in these complexes was scrutinized by various studies. Because of strong intramolecular charge transfer these D-A based AIEgens exhibited solvatochromism. Further, AIE property of the complexes C1 and C3 was exploited toward detection of CO2. © 2018 American Chemical Society.
Design and synthesis of heteroleptic Ni(II) dipyrrin complexes for electrochemical proton reduction reactions: Cyclic voltammetric and theoretical studies
(Elsevier B.V., 2024) Rajendra Prasad Paitandi; Indranil Mondal; Yogesh Kumar; Nikhil Kumar Singh; Daya Shankar Pandey
The effect of nuclearity on electrochemical hydrogen generation using new heteroleptic Ni(II) complexes containing redox-active dipyrrin and dithiocarbamate ligands has been described. Complexes 1–2 have been meticulously characterized by spectroscopic studies (ESI-MS, IR, 1H, 13C NMR, UV–vis) and their structures unambiguously confirmed by X-ray single crystal analyses. Electrocatalytic properties of the complexes toward hydrogen evolution reaction have been investigated by cyclic voltammetric studies in an organic medium in the presence of acetic acid as a weak proton source. Notably, complexes 1 and 2 produce H2 via doubly reduced Ni(II) species i.e. Ni(0) in the presence of acetic acid. Further, these complexes exhibited significant electrocatalytic activity (TOF: 264 (1) and 650 s−1 (2). Controlled potential electrolysis established a minimum Faradaic efficiency of 92 (1) and 96 % (2). Complex 2 exhibited higher turnover frequency relative to 1, while 1 showed lower overpotential (0.35 V) in comparison to 2 (0.45 V). The stability of the complexes and the amount of produced H2 has been investigated by bulk electrolysis study. A tentative mechanism (ECEC; E, electrons and C, chemical steps) and involved intermediate species for the proton reduction reaction for 1 has been established by theoretical studies. © 2024 Elsevier B.V.
DNA/protein binding and anticancer activity of ruthenium (II) arene complexes based on quinoline dipyrrin
(Elsevier B.V., 2023) Nikhil Kumar Singh; Yogesh Kumar; Rajendra Prasad Paitandi; Rajan Kumar Tiwari; Ajay Kumar; Daya Shankar Pandey
Arene ruthenium complexes [(η6–arene)Ru(L)Cl] (η6–arene = benzene, R1; p-cymene, R2) containing the chelating ligand (2–chloro–3–(di(1H–pyrrol–2–yl)methyl)quinoline) (L) have been synthesized and carefully characterized by various studies (1H and 13C NMR, IR, ESI–MS, UV–vis). The structure of R1 has been verified by X-ray single crystal analyses. Binding of the complexes with calf thymus DNA (CT–DNA) has been investigated by absorption titration, ethidium bromide (EB) displacement and viscosity measurements. Experimental binding constants (5.1 × 104 M−1, R1; 5.7 × 104 M−1, R2) suggested appreciable bonding of the complexes with CT–DNA. Fluorescence, synchronous and 3D fluorescence spectroscopic studies showed that complexes strongly bind with bovine serum albumin. Intercalative interaction of the complexes with DNA has been further supported by DFT studies. Our studies have shown potential anticancer activity of both the complexes R1 and R2 against T cell lymphoma. Among these complexes R2 showed better anticancer activity relative to R1 (IC50, R1, 30 μM and R2, 20 μM). © 2022
Effect of substituents on photophysical and aggregation behaviour in quinoline based bis-terpyridine Zn(II) complexes
(Elsevier S.A., 2019) Vishwa Deepak Singh; Bhupendra Kumar Dwivedi; Rajendra Prasad Paitandi; Yogesh Kumar; Daya Shankar Pandey
Synthesis of the terpyridine based novel Zn(II) complexes (C1–C3) have been described. Characterization of these complexes has been achieved by spectroscopic studies (IR, 1H, 13C, 19F, HRMS, UV/Vis and fluorescence) and structure of C1 determined by X-ray single crystal analyses. Cautious tuning by incorporating appropriate substituents (–H; C1, –CH3; C2 and –OCH3; C3) enabled the complexes to exhibit solvent dependent emission indicative of more polarized excited state probably due to enhanced intramolecular charge transfer (ICT). Occurrence of aggregation induced emission (AIE) in C3 has been validated by solid state emission and vital role of RIR in inducing AIE upon aggregation by fluorescence lifetime experiments. The role of solvent and substituents on photophysical behaviour and morphology of the complexes has been investigated by UV/Vis, emission and scanning electron microscopy (SEM). As well, lowering of the energy gap between HOMO and LUMO by electron donating substituents –CH3 (C2) and –OCH3 (C3) has been supported by DFT studies. © 2018 Elsevier B.V.
Heteroleptic arene Ru(ii) dipyrrinato complexes: DNA, protein binding and anti-cancer activity against the ACHN cancer cell line
(Royal Society of Chemistry, 2016) Rakesh Kumar Gupta; Amit Kumar; Rajendra Prasad Paitandi; Roop Shikha Singh; Sujay Mukhopadhyay; Shiv Prakash Verma; Parimal Das; Daya Shankar Pandey
Four organometallic complexes [(η6-C6H6)RuCl(pmpzdpm)], 1; [(η6-C6H6)RuCl(pypzdpm)], 2; [(η6-C10H14)RuCl(pmpzdpm)], 3 and [(η6-C10H14)RuCl(pypzdpm)], 4 containing 5-(2-pyrimidyl-piperazine)phenyldipyrromethene (pmpzdpm) and 5-(2-pyridylpiperazine)phenyldipyrromethene (pypzdpm) have been designed and synthesized. The complexes 1-4 have been fully characterized by elemental analyses and spectroscopic studies (ESI-MS, IR, 1H, 13C NMR, UV-vis). Their electrostatic/intercalative interaction with CT DNA has been investigated by UV-vis and competitive ethidium bromide displacement studies while their protein binding affinity toward bovine serum albumin (BSA) was realized by UV-vis, fluorescence, synchronous and three dimensional (3D) fluorescence studies. The interaction with DNA and protein has further been validated by in silico studies. Cellular uptake, in vitro cytotoxicity and flow cytometric analyses have been performed to determine the mode of cell death against the kidney cancer cell line ACHN. Cell cycle analysis suggested that the complexes cause cell cycle arrest in the subG1 phase and overall results indicated that the in vitro antitumor activity of 1-4 lies in the order of 3 > 4 > 1 > 2 (IC50, 7.0 1; 8.0 2; 2.0 3; 4.0 μM, 4). © The Royal Society of Chemistry 2016.
Influence of substituents on DNA and protein binding of cyclometalated Ir(III) complexes and anticancer activity
(Royal Society of Chemistry, 2017) Sujay Mukhopadhyay; Roop Shikha Singh; Rajendra Prasad Paitandi; Gunjan Sharma; Biplob Koch; Daya Shankar Pandey
Synthesis of terpyridyl based ligands 3-([2,2′:6′,2′′-terpyridin]-4′-yl)-7-methoxy-2-(methylthio)-quinolone, (L1); 3-([2,2′:6′,2′′-terpyridin]-4′-yl)-6-methoxyquinolin-2(1H)-one, (L2); 3-([2,2′-:6′,2′′-terpyridin]-4′-yl)-6-methylquinolin-2(1H)-one (L3) and cyclometalated iridium(iii) complexes [[Ir(ppy)2L1]+PF6- (1), [Ir(ppy)2L2]+PF6- (2), [Ir(ppy)2L3]+PF6- (3) (2-phenylpyridine = Hppy)] involving these ligands has been described. The ligands L1-L3 and complexes 1-3 have been thoroughly characterized by elemental analyses, spectral studies (IR, 1H, 13C NMR, UV/vis and fluorescence) ESI-MS, and the structure of 3 has been unambiguously authenticated by single crystal X-ray analyses. UV/vis, fluorescence and circular dichroism spectroscopic studies showed rather efficient binding of 1 with CT-DNA (calf thymus DNA) and BSA (bovine serum albumin) relative to 2 and 3. Molecular docking studies unveiled binding of 1-3 with minor groove of CT-DNA via van der Waal's forces and electrostatically with the hydrophobic moiety of HSA (human serum albumin). The ligands and complexes exhibited moderate cytotoxicity towards MDA-MB-231 (breast cancer cell line) and significant influence on HeLa (cervical cancer cell line) cells. Cytotoxicity, morphological changes, and apoptosis have been followed by MTT (3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazoliumbromide) assay, Hoechst 33342/PI (PI = propidium iodide) staining, cell cycle analysis by FACS (fluorescence activated cell sorting), and ROS (reactive oxygen species) generation by DCFH-DA (dichlorodihydrofluorescein diacetate) dye. Confocal microscopy images revealed that the drug efficiently initiates apoptosis in the cell cytosol. The IC50 values showed superior cytotoxicity of 1-3 against the HeLa cell line relative to cisplatin, and their ability to induce apoptosis is in the order 1 > 2 > 3. © The Royal Society of Chemistry 2017.
Interaction of ferrocene appended Ru(II), Rh(III) and Ir(III) dipyrrinato complexes with DNA/protein, molecular docking and antitumor activity
(Elsevier Masson SAS, 2014) Rajendra Prasad Paitandi; Rakesh Kumar Gupta; Roop Shikha Singh; Gunjan Sharma; Biplob Koch; Daya Shankar Pandey
Efficacy of the ferrocene appended piano-stool dipyrrinato complexes [(η6-C6H6)RuCl(fcdpm)] (1), [(η6-C10H14)RuCl(fcdpm)] (2), [(η6-C12H18)RuCl(fcdpm)] (3) [(η5-C5Me5)RhCl(fcdpm)] (4) and [(η5-C5Me5)IrCl(fcdpm)] (5) [fcdpm = 5-ferrocenyldipyrromethene] toward anticancer activity have been described. Binding of the complexes with calf thymus DNA (CT-DNA) and BSA (bovine serum albumin) have been thoroughly investigated by UV-Vis and fluorescence spectroscopy. Binding constants for 1-5 (range, 104-105 M-1) validated their efficient binding with CT-DNA. Molecular docking studies revealed interaction through minor groove of the DNA, on the other hand these also interact through hydrophobic residues of the protein, particularly cavity in the subdomain IIA. In vitro anticancer activity have been scrutinized by MTT assay, acridine orange/ethidium bromide (AO/EtBr) fluorescence staining, and DNA ladder (fragmentation) assay against Dalton's Lymphoma (DL) cells. Present study revealed that rhodium complex (4) is more effective relative to ruthenium (1-3) and iridium (5) complexes. © 2014 Elsevier Masson SAS. All rights reserved.
Morphological tuning via structural modulations in AIE luminogens with the minimum number of possible variables and their use in live cell imaging
(Royal Society of Chemistry, 2015) Roop Shikha Singh; Rakesh Kumar Gupta; Rajendra Prasad Paitandi; Mrigendra Dubey; Gunjan Sharma; Biplob Koch; Daya Shankar Pandey
With intent to fine tune the morphological and photophysical properties, three novel AIE luminogens (BQ1-BQ3) based on quinoline-BODIPY have been synthesized. A judicious choice of substituents (-H, -CH3, -OCH3) in these systems led to nanoballs in BQ1 and BQ2, while in BQ3 it led to reticulated nanofibers with diverse photophysical behaviours. This journal is © The Royal Society of Chemistry 2015.
Polymerization of 1-(2-Propynyl)-3-methylimidazolium Bromide using Cyclometalated Pd(II) Catalysts and Study of the Interaction of Ensuing Oligomer with BSA
(Wiley-Blackwell, 2017) Sujay Mukhopadhyay; Kheyanath Mitra; Rajendra Prasad Paitandi; Roop Shikha Singh; Shikha Singh; Biswajit Ray; Daya Shankar Pandey
Two novel cyclometalated binuclear chloro-bridged palladium based catalysts, {(PdClL1)2} (1) and {(PdClL2)2} (2) have been synthesized by reacting PdCl2 with 4-nitro-(benzylidene-(4-tert-butyl-phenyl)-amine (L1) and 4-methylester-(benzylidene-(4-tert-butyl-phenyl)-amine (L2), respectively. These have been characterized by elemental analyses, spectroscopic studies (IR, 1H, 13C NMR, ESI-MS), and their structures have been authenticated by X-ray single crystal analyses. Polymerization of ionic liquid monomer using these catalysts has been investigated. 1 exhibited best catalytic activity and each catalyst afforded both conducting and fluorescent oligomers and high molecular weight polymers. Resulting oligomers and polymers have been characterized by spectroscopic and conductivity, GPC, SEM-EDAX, PXRD studies. Oligomers are fluorescent and their emission intensity enhances upon interaction with anions. Binding behaviour of oligomers has been examined with BSA. Quenching of the intrinsic fluorescence of BSA in presence of oligomers have been studied by steady state, synchronous, and 3D fluorescence spectroscopy and changes in secondary structure quantified by CD spectroscopy. © 2017 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim
Pyrazole appended quinoline-BODIPY based arene ruthenium complexes: their anticancer activity and potential applications in cellular imaging
(Royal Society of Chemistry, 2018) Rajendra Prasad Paitandi; Vinay Sharma; Vishwa Deepak Singh; Bhupendra Kumar Dwivedi; Shaikh M. Mobin; Daya Shankar Pandey
Synthesis of an entirely new series of arene ruthenium complexes [Ru(η6-C6H6)(L1)Cl]PF6, (1), [Ru(η6-C10H14)(L1)Cl]PF6 (2), [Ru(η6-C6H6)(L2)Cl]PF6 (3) and [Ru(η6-C10H14)(L2)Cl]PF6 (4) involving 5-[2-(1H-pyrazol-1-yl)quinoline]-BODIPY (L1) and 5-[6-methoxy-2-(1H-pyrazol-1-yl)quinoline]-BODIPY (L2) was described. The ligands and complexes were thoroughly characterized by various physicochemical techniques and the structures of L1, 1 and 4 were determined by X-ray single crystal analyses. Photo-/ and electrochemical property, DNA binding, cytotoxicity, cellular uptake and apoptotic studies on 1-4 were performed by various methods, while singlet oxygen-mediated cytotoxicity via photo-irradiation by visible light was supported by 1,3-diphenylisobenzofuran titration studies. Binding of the complexes in the minor groove of CT-DNA via van der Waals forces and electrostatic interactions was affirmed by molecular docking studies. In vitro antiproliferative activity and photocytotoxicity of 1-4 were examined against the human cervical cancer cell line (HeLa) which clearly showed that these are extremely photocytotoxic under visible light (400-700 nm, 10 J cm−2; IC50 49.15, 1; 25.18, 2; 15.85, 3; 12.87, 4), less toxic in the dark (IC50 > 100 μM) and preferentially accumulate in the lysosome of the HeLa cells. Further, these complexes behave as a potential theranostic agent and their ability to kill cancer cells under visible light lies in the order 4 > 3 > 2 > 1. © The Royal Society of Chemistry.
Recent developments in metal dipyrrin complexes: Design, synthesis, and applications
(Elsevier B.V., 2020) Roop Shikha Singh; Rajendra Prasad Paitandi; Rakesh Kumar Gupta; Daya Shankar Pandey
This in-depth review covers recent developments in the area of metal dipyrrinato complexes based on dipyrrins, a unique class of compounds which have fascinated the scientific community due to their ease of syntheses, interesting photophysical properties, and diverse architectures arising from self-assembly. Dipyrrins can form stable, highly crystalline and neutral complexes with a various metal ions however underdeveloped photochemistry and photophysics of these compounds have limited their technological applications. Recently, the area of metal dipyrrin complexes has witnessed a large surge due to their promising use in the development of bright and stable emitters which find wide applications in sensing, materials science, generation of infinite architecture through self-assembly, and catalysis. In the present review, Section 2 describes syntheses of dipyrrins and their analogues; Section 3 covers the geometrical consideration of metal-dipyrrin complexes. Section 4 focuses on synthesis, while Section 5 includes properties of metal-dipyrrin complexes and their applications in sensing, supra-molecular assembly, coordination polymers, anticancer agents, nanotechnology and catalysis. © 2020
Solvent-Dependent Self-Assembly and Aggregation-Induced Emission in Zn(II) Complexes Containing Phenothiazine-Based Terpyridine Ligand and Its Efficacy in Pyrophosphate Sensing
(American Chemical Society, 2018) Vishwa Deepak Singh; Roop Shikha Singh; Rajendra Prasad Paitandi; Bhupendra Kumar Dwivedi; Biswajit Maiti; Daya Shankar Pandey
Zn(II) complexes MTPY-ZnCl2 (C1) and MTPY-Zn(NO3)2 (C2) based on a new D-A type ligand MTPY involving phenothiazine donor and terpyridine acceptor units have been described. The ligand MTPY and complexes C1 and C2 display intramolecular charge transfer and substantial solvatochromism. Solid-state emission studies on MTPY further substantiated the occurrence of concentration-induced emission in this molecule. In addition, the complexes C1 and C2 displayed a solvent-dependent self-assembly which has been examined as a function of the hydrophilic and hydrophobic nature of the solvent systems. The role of hydrophilicity/hydrophobicity of a solvent and compounds on morphology and emission characteristics of the self-assembled aggregates has been investigated by UV-vis, emission, and scanning electron microscopy studies. In addition, it has been categorically shown that aggregation-induced emission in C1 offers a simple, sensitive, and rapid means for the detection of pyrophosphates (PPi) in the aqueous medium. Job's plot analysis suggested a 3:1 binding stoichiometry between C1 and PPi, which has been supported by electrospray ionization mass spectrometry and density functional theory. Further, higher affinity of PPi toward C1 over C2 has also been rationalized by theoretical studies. © 2018 American Chemical Society.
Spacer length dependent architectural diversity in bis-dipyrrin copper(II) complexes
(Royal Society of Chemistry, 2017) Rajendra Prasad Paitandi; Roop Shikha Singh; Sujay Mukhopadhyay; Ashish Kumar; Daya Shankar Pandey
A series of copper(ii) complexes (1-9 and 3′) derived from bis-dipyrrin ligands (L1-L9 and L3′) with diverse spacer lengths [-(CH2)n-] have been described. Structural diversities in these complexes have been explicitly established by spectral and structural studies on these and a closely related nickel(ii) complex (3′′). All the ligands and complexes have been thoroughly characterized by spectroscopic studies (ESI-MS, IR, 1H, 13C NMR, UV/vis) and structures of 2, 3′, 3′′, 6, 8 and 9 were determined by X-ray single crystal analyses. It has been unambiguously established that ligands with n ≤ 6 gave heteroleptic binuclear (1-5), while those with n ≥ 7 yielded homoleptic mononuclear (6-9) bis-dipyrrinato complexes. Spectral and structural studies revealed distorted square planar (1-5) and distorted tetrahedral geometries (6-9) about the copper(ii) centre in these complexes which has further been evidenced by EPR and electrochemical studies. Structural differences based on the odd and even number of methylene spacers in these complexes have been supported by DFT studies. A line between the syn- and anti-conformations of the complexes has been drawn on the basis of a limiting spacer length. © The Royal Society of Chemistry.
Substituent-directed ESIPT-coupled Aggregation-induced Emission in Near-infrared-emitting Quinazoline Derivatives
(Wiley-VCH Verlag, 2018) Bhupendra Kumar Dwivedi; Vishwa Deepak Singh; Rajendra Prasad Paitandi; Daya Shankar Pandey
A series of ESIPT (excited state intramolecular proton transfer) active systems (HQz1–HQz6) derived from quinazoline have been reported. The ESIPT emission for these derivatives gets completely quenched in solvents with diverse polarities which have been restored via aggregation-induced emission (AIE) with large Stokes shift (up to 314 nm). It varied from 450 to 701 nm just by altering substituents at the para position of hydroxy group in the central phenyl ring. As well, HQz1–HQz6 displayed solid state emission [∼455 (blue) to ∼704 nm (red)]. The formyl group on the central hydroxy-phenyl ring of these derivatives induces ESIPT by increasing acidity of the hydroxy proton which has been followed by 1H NMR studies. Further, it has been clearly shown that emission colour and aggregate morphology can be fine tuned by incorporating apt substituents. The present study offers a simple route to obtain colour tunable ESIPT emission via AIE which is very important for biological imaging and fabrication of optoelectronic devices. © 2018 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim
Synthesis, characterization, DNA binding and cytotoxicity of fluoro-dipyrrin based arene ruthenium(II) complexes
(Elsevier S.A., 2017) Rajendra Prasad Paitandi; Roop Shikha Singh; Sujay Mukhopadhyay; Gunjan Sharma; Biplob Koch; Pratap Vishnoi; Daya Shankar Pandey
Synthesis of four new arene ruthenium(II) complexes [(η6-C10H14)RuCl(MFPdpm)] (1); [(η6-C12H18)Ru-Cl(MFPdpm)] (2); [(η6-C10H14)RuCl(PFPdpm)] (3) and [(η6-C12H18)RuCl(PFPdpm)] (4) containing dipyrrin ligands 5-(4-fluoro)phenyldipyrromethene (MFPdpm) and 5-(penta-fluoro)phenyldipyrromethene (PFPdpm) have been described. The ligands and complexes have been thoroughly characterized by elemental analyses, spectroscopic studies (ESI-MS, IR,1H,13C NMR, UV–Vis) and structure of the representative complex 4 determined by X-ray single crystal analyses. DNA binding activities of 1–4 have been investigated by UV–Vis and fluorescence spectroscopy and their binding through the minor groove of DNA has been established by molecular docking studies. The complexes 1–4 exhibit significant cytotoxicity toward human lung cancer cell line (A549). Cytotoxicity, morphological changes, and apoptosis studies have been evaluated through MTT assay, Hoechst 33342/PI staining, and cell cycle analysis by fluorescence activated cell sorting (FACS). In vitro antitumor activity and cytotoxicity of the complexes lie in the order 4 > 3 > 2 > 1. © 2016 Elsevier B.V.