FALGUNI CHANDRA - Academia.edu (original) (raw)
Papers by FALGUNI CHANDRA
Polymers
Despite the enormous environmental damage caused by plastic waste, it makes up over one-third of ... more Despite the enormous environmental damage caused by plastic waste, it makes up over one-third of globally produced plastics. Polyethylene (PE) wastes have low recycling but high production rates. Towards the construction of ionic solar cells from PE, the present work describes the loading of a bioactive photoacid phycocyanobilin (PCB) dye from the pigment of Spirulina blue–green algae (as a natural resource) on low-density polyethylene (LDPE) plastic film. Dyeing was confirmed by X-ray photoelectron spectroscopy (XPS). Upon excitation of the Soret-band (400 nm), the photoluminescence (PL) spectra of PCB in neat solvents revealed two prominent emission peaks at 450–550 and 600–700 nm. The first band assigned to bilirubin-like (PCBBR) species predominated the spectral profile in the highly rigid solvent glycerol and upon loading 0.45 % (w/w) of the dye on plastic. The photoluminescence excitation (PLE) spectra of PCB for the second region (Q-band) at 672 nm in the same solvents confir...
Nanomaterials
In this study, we aimed to elucidate the effects of temperature on the photoluminescence from ZnO... more In this study, we aimed to elucidate the effects of temperature on the photoluminescence from ZnO–SiO2 nanocomposite and to describe the preparation of SiO2-coated ZnO nanocrystals using a chemical precipitation method, as confirmed by Fourier transform infrared (FTIR) and powder X-ray diffraction analysis (XRD) techniques. Analyses using high-resolution transmission microscopy (TEM), energy-dispersive X-ray spectroscopy (EDX), dynamic light scattering (DLS), and electrophoretic light scattering (ELS) techniques showed that the new nanocomposite has an average size of 70 nm and 90% silica. Diffuse reflectance spectroscopy (DRS), photoluminescence (PL), and photoluminescence-excitation (PLE) measurements at different temperatures revealed two emission bands at 385 and 590 nm when the nanomaterials were excited at 325 nm. The UV and yellow emission bands were attributed to the radiative recombination and surface defects. The variable-temperature, time-resolved photoluminescence (VT-TR...
Dyes and Pigments, 2022
Abstract Herein, we present synthesis, photophysical and photocatalytic aspects of four mononucle... more Abstract Herein, we present synthesis, photophysical and photocatalytic aspects of four mononuclear luminescent iridium complexes ([1]+ - [4]+) incorporating cyclometallating benzimidazole-based (L1 and L2) and phenanthroline pyrazine-based (L3 – L5) ligands. Several analytical techniques were used for the characterization of the complexes. The structural elucidation of [2]+ and [3]+ using x-ray crystallography show a distorted Oh structure with nitrogen donors of cyclometallating ligands are in trans-direction. All the complexes are emitting in the orange-red region and displayed moderately good quantum yield. The complexes have also shown moderately good luminescence lifetime (τ = 80–1900 ns) in different solvents. Importantly, the complex [3]+ exhibits comparative longer emission lifetime (τ = 1800 ns) in water at ambient condition. The complexes have shown moderately good photocatalytic efficacy towards azo dyes degradation in aqueous solution. The mechanistic investigation suggests that in the presence of light in aqueous medium the complexes induce the generation of (HO•/(O2• −) species which is responsible for the photodecomposition of azo dyes.
An entry from the Cambridge Structural Database, the world's repository for small molecule cr... more An entry from the Cambridge Structural Database, the world's repository for small molecule crystal structures. The entry contains experimental data from a crystal diffraction study. The deposited dataset for this entry is freely available from the CCDC and typically includes 3D coordinates, cell parameters, space group, experimental conditions and quality measures.
An entry from the Cambridge Structural Database, the world's repository for small molecule cr... more An entry from the Cambridge Structural Database, the world's repository for small molecule crystal structures. The entry contains experimental data from a crystal diffraction study. The deposited dataset for this entry is freely available from the CCDC and typically includes 3D coordinates, cell parameters, space group, experimental conditions and quality measures.
An entry from the Cambridge Structural Database, the world's repository for small molecule cr... more An entry from the Cambridge Structural Database, the world's repository for small molecule crystal structures. The entry contains experimental data from a crystal diffraction study. The deposited dataset for this entry is freely available from the CCDC and typically includes 3D coordinates, cell parameters, space group, experimental conditions and quality measures.
An entry from the Cambridge Structural Database, the world's repository for small molecule cr... more An entry from the Cambridge Structural Database, the world's repository for small molecule crystal structures. The entry contains experimental data from a crystal diffraction study. The deposited dataset for this entry is freely available from the CCDC and typically includes 3D coordinates, cell parameters, space group, experimental conditions and quality measures.
An entry from the Cambridge Structural Database, the world's repository for small molecule cr... more An entry from the Cambridge Structural Database, the world's repository for small molecule crystal structures. The entry contains experimental data from a crystal diffraction study. The deposited dataset for this entry is freely available from the CCDC and typically includes 3D coordinates, cell parameters, space group, experimental conditions and quality measures.
Journal of Molecular Liquids, 2021
Dyes and Pigments, 2021
Abstract Herein, we present synthesis, photophysical and photocatalytic aspects of four mononucle... more Abstract Herein, we present synthesis, photophysical and photocatalytic aspects of four mononuclear luminescent iridium complexes ([1]+ - [4]+) incorporating cyclometallating benzimidazole-based (L1 and L2) and phenanthroline pyrazine-based (L3 – L5) ligands. Several analytical techniques were used for the characterization of the complexes. The structural elucidation of [2]+ and [3]+ using x-ray crystallography show a distorted Oh structure with nitrogen donors of cyclometallating ligands are in trans-direction. All the complexes are emitting in the orange-red region and displayed moderately good quantum yield. The complexes have also shown moderately good luminescence lifetime (τ = 80–1900 ns) in different solvents. Importantly, the complex [3]+ exhibits comparative longer emission lifetime (τ = 1800 ns) in water at ambient condition. The complexes have shown moderately good photocatalytic efficacy towards azo dyes degradation in aqueous solution. The mechanistic investigation suggests that in the presence of light in aqueous medium the complexes induce the generation of (HO•/(O2• −) species which is responsible for the photodecomposition of azo dyes.
![Research paper thumbnail of Supramolecular Encapsulation of a Neurotransmitter Serotonin by Cucurbit[7]uril](https://attachments.academia-assets.com/95314398/thumbnails/1.jpg)
](Frontiers in Chemistry, 2020
pH-dependent host-guest complexation of a monoamine neurotransmitter, Serotonin, with cucurbit[7]... more pH-dependent host-guest complexation of a monoamine neurotransmitter, Serotonin, with cucurbit[7]uril has been thoroughly investigated. The binding phenomena were explored using steady-state and time-resolved fluorescence spectroscopy at different pH values. At lower pH, i.e., protonated Serotonin, the binding affinity with cucurbit[7]uril was significantly higher compared to higher pH. Furthermore, detailed NMR titration experiments depicted the solution structure of the host-guest complex through the complexation induced chemical shift values. A competitive binding assay with cesium ions at pD 2.8 was subsequently performed for the further manifestation of the binding. Finally, the molecular docking studies provided well-documented proof of the 1:1 inclusion complex and the geometry of the complex. We believe that understanding from such studies can be important for pH-controlled delivery of serotonin for biological applications.
A unique radiative decay engineering strategy using DNA microviscosity for the generation of ruth... more A unique radiative decay engineering strategy using DNA microviscosity for the generation of ruthenium polypyridyl complex (RPCs) mediated singlet oxygen for selective damage of DNA and killing cancer cells is reported. This investigation also demonstarte the effect of light-driven RPCs on bacterial growth arrest, through DNA nick, and differential localization in cancer and non-cancer cells. Moreover, upon binding with DNA, RPCs experience high local microviscosity, which causes significant enhancement of the excited state lifetime and thus generates singlet oxygen. The visible-light-triggered singlet-oxygen efficiently produce nick in DNA and inhibits bacterial growth. RPCs also localize inside the nucleus of the cancer cell and in the vicinity of the nuclear membrane of non-cancerous cells, confirmed by live-cell confocal microscopy. The results provide a facile platform for the novel antibiotic intended discovery combined with cancer therapy.
Spectrochimica Acta Part A: Molecular and Biomolecular Spectroscopy, 2018
A "naked-eye" detection of health hazardous bisulfite (HSO 3 −) and hypochlorite (ClO −) using an... more A "naked-eye" detection of health hazardous bisulfite (HSO 3 −) and hypochlorite (ClO −) using an indicator dye (Quinaldine Red, QR) in a wide range of pH is demonstrated. The molecule contains a quinoline moiety linked to an N,N-dimethylaniline moiety with a conjugated double bond. Treatment of QR with HSO 3 − and ClO − , in aqueous solution at near-neutral pH, resulted in a colorless product with high selectivity and sensitivity. The detection limit was 47.8 μM and 0.2 μM for HSO 3 − and ClO − respectively. However, ClO − was 50 times more sensitive and with 2 times faster response compared to HSO 3 −. The detail characterization and related analysis demonstrate the potential of QR for a rapid, robust and highly efficient colorimetric sensor for the practical applications to detect hypochlorite in water samples.
European Journal of Organic Chemistry, 2017
An efficient microwave-assisted Sonogashira-coupling protocol for peri-functionalised perylenemon... more An efficient microwave-assisted Sonogashira-coupling protocol for peri-functionalised perylenemonoimide dye derivative is presented. This method is significantly faster than conventional coupling method providing a moderate to good yield and interesting optoelectronic properties. The electronic communication between electron-rich aryl and poly aryl groups with the perylene core via C≡C bonds is investigated.
Dalton transactions (Cambridge, England : 2003), Jan 25, 2018
Five mononuclear cyclometalated iridium complexes [1](PF6)-[5](PF6) were prepared using imidazole... more Five mononuclear cyclometalated iridium complexes [1](PF6)-[5](PF6) were prepared using imidazole-based ligands of varying alkyl chain length. The complexes were characterised by various analytical techniques. The single crystal X-ray structures of [2](PF6), [3](PF6) and [4](PF6) revealed the expected distorted Oh structures around the metal centre; however, the chain length was found to play a crucial role in deciding the overall geometry. Theoretical investigations demonstrated that the HOMOs were mainly contributed by iridium and cyclometalated ligands, whereas the LUMOs were constituted from bpy/phen units. The complexes were found to be luminescent with a moderate emission quantum yield and lifetime in CH3CN. The in vitro growth inhibition assay of the complexes with a shorter alkyl chain ([4]+ and [5]+) displayed higher anticancer activity (IC50 < 0.5 μM) compared to the complexes with a longer alkyl chain ([1]+-[3]+) (IC50 < 30 μM) against human breast cancer (MCF-7) ce...
![Research paper thumbnail of Encapsulation and modulation of protolytic equilibrium of β-carboline-based norharmane drug by cucurbit[7]uril and micellar environments for enhanced cellular uptake](https://attachments.academia-assets.com/95314390/thumbnails/1.jpg)
](Colloids and surfaces. B, Biointerfaces, Jan 31, 2018
The effect of supramolecular nanocavity on photophysical and acid-dissociation properties of Norh... more The effect of supramolecular nanocavity on photophysical and acid-dissociation properties of Norharmane (NHM), a physiologically important, anxiety control and memory-enhancing β-carboline-based drug, has been investigated using steady-state absorption and fluorescence spectroscopy. Self-assembled organization derived from surfactants and rigid water-soluble macrocyclic host Cucurbit[7]uril (CB7) have been selected for this investigation. The confined-space offered by the supramolecular assemblies modulates the pK value of NHM (up to 3 units) as it can exist in two protolytic forms at near neutral pH. Therefore, the pH-dependent binding properties, modulation of pK value and its consequences on the photophysical, chemical and solubility properties are investigated in detail. This investigation shows a large shift in the protolytic equilibrium which in turn causes ca. 15 times solubility-enhancement at near neutral pH. Moreover, the effect of enhanced solubility has been further inve...
Inorganic Chemistry, 2017
Two mononuclear ruthenium complexes [(bpy) 2 Ru II L 1 /L 2 ](ClO 4) 2 ([1] 2+ /[2] 2+) (bpy-2,2′... more Two mononuclear ruthenium complexes [(bpy) 2 Ru II L 1 /L 2 ](ClO 4) 2 ([1] 2+ /[2] 2+) (bpy-2,2′ bipyridine, L 1 = 2,3-di(pyridin-2-yl)pyrazino[2,3-f ][1,10]phenanthroline) and L 2 = 2,3-di(thiophen-2-yl)pyrazino[2,3-f ][1,10]phenanthroline have been synthesized. The complexes have been characterized using various analytical techniques. The complex [1] 2+ has further been characterized by its single crystal X-ray structure suggesting ruthenium is coordinating through the N donors of phenanthroline end. Theoretical investigation suggests that the HOMOs of both complexes are composed of pyridine and pyrazine unit of ligands L 1 and L 2 whereas the LUMOs are formed by the contribution of bipyridine units. The low energy bands at ∼480 nm of the complexes can be assigned as MLCT with partial contribution from ligand transitions, whereas the rest are ligand centered. The complexes have shown Ru II /Ru III oxidation couples at E 1/2 at 1.26 (70 mV) V and 1.28 (62 mV) V for [1] 2+ and [2] 2+ vs Ag/AgCl, respectively, suggesting no significant role of distal thiophene or pyridine units of the ligands. The complexes are emissive and display solvent dependent emission properties. Both complexes have shown highest emission quantum yield and lifetime in DMSO (ϕ = 0.05 and τ avg = 460 ns and λ max em at 620 nm for [1] 2+ ; ϕ = 0.043 and τ avg = 425 ns and λ max em at 635 nm for [2] 2+). Further, the long luminescent lifetime of these complexes has been utilized to generate reactive oxygen species for efficient azo dye decomposition.
Physical Chemistry Chemical Physics, 2017
Enzymes are biological catalysts that can vastly accelerate the reaction rate of a substrate by a... more Enzymes are biological catalysts that can vastly accelerate the reaction rate of a substrate by accommodating it within the active site.
Polymers
Despite the enormous environmental damage caused by plastic waste, it makes up over one-third of ... more Despite the enormous environmental damage caused by plastic waste, it makes up over one-third of globally produced plastics. Polyethylene (PE) wastes have low recycling but high production rates. Towards the construction of ionic solar cells from PE, the present work describes the loading of a bioactive photoacid phycocyanobilin (PCB) dye from the pigment of Spirulina blue–green algae (as a natural resource) on low-density polyethylene (LDPE) plastic film. Dyeing was confirmed by X-ray photoelectron spectroscopy (XPS). Upon excitation of the Soret-band (400 nm), the photoluminescence (PL) spectra of PCB in neat solvents revealed two prominent emission peaks at 450–550 and 600–700 nm. The first band assigned to bilirubin-like (PCBBR) species predominated the spectral profile in the highly rigid solvent glycerol and upon loading 0.45 % (w/w) of the dye on plastic. The photoluminescence excitation (PLE) spectra of PCB for the second region (Q-band) at 672 nm in the same solvents confir...
Nanomaterials
In this study, we aimed to elucidate the effects of temperature on the photoluminescence from ZnO... more In this study, we aimed to elucidate the effects of temperature on the photoluminescence from ZnO–SiO2 nanocomposite and to describe the preparation of SiO2-coated ZnO nanocrystals using a chemical precipitation method, as confirmed by Fourier transform infrared (FTIR) and powder X-ray diffraction analysis (XRD) techniques. Analyses using high-resolution transmission microscopy (TEM), energy-dispersive X-ray spectroscopy (EDX), dynamic light scattering (DLS), and electrophoretic light scattering (ELS) techniques showed that the new nanocomposite has an average size of 70 nm and 90% silica. Diffuse reflectance spectroscopy (DRS), photoluminescence (PL), and photoluminescence-excitation (PLE) measurements at different temperatures revealed two emission bands at 385 and 590 nm when the nanomaterials were excited at 325 nm. The UV and yellow emission bands were attributed to the radiative recombination and surface defects. The variable-temperature, time-resolved photoluminescence (VT-TR...
Dyes and Pigments, 2022
Abstract Herein, we present synthesis, photophysical and photocatalytic aspects of four mononucle... more Abstract Herein, we present synthesis, photophysical and photocatalytic aspects of four mononuclear luminescent iridium complexes ([1]+ - [4]+) incorporating cyclometallating benzimidazole-based (L1 and L2) and phenanthroline pyrazine-based (L3 – L5) ligands. Several analytical techniques were used for the characterization of the complexes. The structural elucidation of [2]+ and [3]+ using x-ray crystallography show a distorted Oh structure with nitrogen donors of cyclometallating ligands are in trans-direction. All the complexes are emitting in the orange-red region and displayed moderately good quantum yield. The complexes have also shown moderately good luminescence lifetime (τ = 80–1900 ns) in different solvents. Importantly, the complex [3]+ exhibits comparative longer emission lifetime (τ = 1800 ns) in water at ambient condition. The complexes have shown moderately good photocatalytic efficacy towards azo dyes degradation in aqueous solution. The mechanistic investigation suggests that in the presence of light in aqueous medium the complexes induce the generation of (HO•/(O2• −) species which is responsible for the photodecomposition of azo dyes.
An entry from the Cambridge Structural Database, the world's repository for small molecule cr... more An entry from the Cambridge Structural Database, the world's repository for small molecule crystal structures. The entry contains experimental data from a crystal diffraction study. The deposited dataset for this entry is freely available from the CCDC and typically includes 3D coordinates, cell parameters, space group, experimental conditions and quality measures.
An entry from the Cambridge Structural Database, the world's repository for small molecule cr... more An entry from the Cambridge Structural Database, the world's repository for small molecule crystal structures. The entry contains experimental data from a crystal diffraction study. The deposited dataset for this entry is freely available from the CCDC and typically includes 3D coordinates, cell parameters, space group, experimental conditions and quality measures.
An entry from the Cambridge Structural Database, the world's repository for small molecule cr... more An entry from the Cambridge Structural Database, the world's repository for small molecule crystal structures. The entry contains experimental data from a crystal diffraction study. The deposited dataset for this entry is freely available from the CCDC and typically includes 3D coordinates, cell parameters, space group, experimental conditions and quality measures.
An entry from the Cambridge Structural Database, the world's repository for small molecule cr... more An entry from the Cambridge Structural Database, the world's repository for small molecule crystal structures. The entry contains experimental data from a crystal diffraction study. The deposited dataset for this entry is freely available from the CCDC and typically includes 3D coordinates, cell parameters, space group, experimental conditions and quality measures.
An entry from the Cambridge Structural Database, the world's repository for small molecule cr... more An entry from the Cambridge Structural Database, the world's repository for small molecule crystal structures. The entry contains experimental data from a crystal diffraction study. The deposited dataset for this entry is freely available from the CCDC and typically includes 3D coordinates, cell parameters, space group, experimental conditions and quality measures.
Journal of Molecular Liquids, 2021
Dyes and Pigments, 2021
Abstract Herein, we present synthesis, photophysical and photocatalytic aspects of four mononucle... more Abstract Herein, we present synthesis, photophysical and photocatalytic aspects of four mononuclear luminescent iridium complexes ([1]+ - [4]+) incorporating cyclometallating benzimidazole-based (L1 and L2) and phenanthroline pyrazine-based (L3 – L5) ligands. Several analytical techniques were used for the characterization of the complexes. The structural elucidation of [2]+ and [3]+ using x-ray crystallography show a distorted Oh structure with nitrogen donors of cyclometallating ligands are in trans-direction. All the complexes are emitting in the orange-red region and displayed moderately good quantum yield. The complexes have also shown moderately good luminescence lifetime (τ = 80–1900 ns) in different solvents. Importantly, the complex [3]+ exhibits comparative longer emission lifetime (τ = 1800 ns) in water at ambient condition. The complexes have shown moderately good photocatalytic efficacy towards azo dyes degradation in aqueous solution. The mechanistic investigation suggests that in the presence of light in aqueous medium the complexes induce the generation of (HO•/(O2• −) species which is responsible for the photodecomposition of azo dyes.
Frontiers in Chemistry, 2020
pH-dependent host-guest complexation of a monoamine neurotransmitter, Serotonin, with cucurbit[7]... more pH-dependent host-guest complexation of a monoamine neurotransmitter, Serotonin, with cucurbit[7]uril has been thoroughly investigated. The binding phenomena were explored using steady-state and time-resolved fluorescence spectroscopy at different pH values. At lower pH, i.e., protonated Serotonin, the binding affinity with cucurbit[7]uril was significantly higher compared to higher pH. Furthermore, detailed NMR titration experiments depicted the solution structure of the host-guest complex through the complexation induced chemical shift values. A competitive binding assay with cesium ions at pD 2.8 was subsequently performed for the further manifestation of the binding. Finally, the molecular docking studies provided well-documented proof of the 1:1 inclusion complex and the geometry of the complex. We believe that understanding from such studies can be important for pH-controlled delivery of serotonin for biological applications.
A unique radiative decay engineering strategy using DNA microviscosity for the generation of ruth... more A unique radiative decay engineering strategy using DNA microviscosity for the generation of ruthenium polypyridyl complex (RPCs) mediated singlet oxygen for selective damage of DNA and killing cancer cells is reported. This investigation also demonstarte the effect of light-driven RPCs on bacterial growth arrest, through DNA nick, and differential localization in cancer and non-cancer cells. Moreover, upon binding with DNA, RPCs experience high local microviscosity, which causes significant enhancement of the excited state lifetime and thus generates singlet oxygen. The visible-light-triggered singlet-oxygen efficiently produce nick in DNA and inhibits bacterial growth. RPCs also localize inside the nucleus of the cancer cell and in the vicinity of the nuclear membrane of non-cancerous cells, confirmed by live-cell confocal microscopy. The results provide a facile platform for the novel antibiotic intended discovery combined with cancer therapy.
Spectrochimica Acta Part A: Molecular and Biomolecular Spectroscopy, 2018
A "naked-eye" detection of health hazardous bisulfite (HSO 3 −) and hypochlorite (ClO −) using an... more A "naked-eye" detection of health hazardous bisulfite (HSO 3 −) and hypochlorite (ClO −) using an indicator dye (Quinaldine Red, QR) in a wide range of pH is demonstrated. The molecule contains a quinoline moiety linked to an N,N-dimethylaniline moiety with a conjugated double bond. Treatment of QR with HSO 3 − and ClO − , in aqueous solution at near-neutral pH, resulted in a colorless product with high selectivity and sensitivity. The detection limit was 47.8 μM and 0.2 μM for HSO 3 − and ClO − respectively. However, ClO − was 50 times more sensitive and with 2 times faster response compared to HSO 3 −. The detail characterization and related analysis demonstrate the potential of QR for a rapid, robust and highly efficient colorimetric sensor for the practical applications to detect hypochlorite in water samples.
European Journal of Organic Chemistry, 2017
An efficient microwave-assisted Sonogashira-coupling protocol for peri-functionalised perylenemon... more An efficient microwave-assisted Sonogashira-coupling protocol for peri-functionalised perylenemonoimide dye derivative is presented. This method is significantly faster than conventional coupling method providing a moderate to good yield and interesting optoelectronic properties. The electronic communication between electron-rich aryl and poly aryl groups with the perylene core via C≡C bonds is investigated.
Dalton transactions (Cambridge, England : 2003), Jan 25, 2018
Five mononuclear cyclometalated iridium complexes [1](PF6)-[5](PF6) were prepared using imidazole... more Five mononuclear cyclometalated iridium complexes [1](PF6)-[5](PF6) were prepared using imidazole-based ligands of varying alkyl chain length. The complexes were characterised by various analytical techniques. The single crystal X-ray structures of [2](PF6), [3](PF6) and [4](PF6) revealed the expected distorted Oh structures around the metal centre; however, the chain length was found to play a crucial role in deciding the overall geometry. Theoretical investigations demonstrated that the HOMOs were mainly contributed by iridium and cyclometalated ligands, whereas the LUMOs were constituted from bpy/phen units. The complexes were found to be luminescent with a moderate emission quantum yield and lifetime in CH3CN. The in vitro growth inhibition assay of the complexes with a shorter alkyl chain ([4]+ and [5]+) displayed higher anticancer activity (IC50 < 0.5 μM) compared to the complexes with a longer alkyl chain ([1]+-[3]+) (IC50 < 30 μM) against human breast cancer (MCF-7) ce...
Colloids and surfaces. B, Biointerfaces, Jan 31, 2018
The effect of supramolecular nanocavity on photophysical and acid-dissociation properties of Norh... more The effect of supramolecular nanocavity on photophysical and acid-dissociation properties of Norharmane (NHM), a physiologically important, anxiety control and memory-enhancing β-carboline-based drug, has been investigated using steady-state absorption and fluorescence spectroscopy. Self-assembled organization derived from surfactants and rigid water-soluble macrocyclic host Cucurbit[7]uril (CB7) have been selected for this investigation. The confined-space offered by the supramolecular assemblies modulates the pK value of NHM (up to 3 units) as it can exist in two protolytic forms at near neutral pH. Therefore, the pH-dependent binding properties, modulation of pK value and its consequences on the photophysical, chemical and solubility properties are investigated in detail. This investigation shows a large shift in the protolytic equilibrium which in turn causes ca. 15 times solubility-enhancement at near neutral pH. Moreover, the effect of enhanced solubility has been further inve...
Inorganic Chemistry, 2017
Two mononuclear ruthenium complexes [(bpy) 2 Ru II L 1 /L 2 ](ClO 4) 2 ([1] 2+ /[2] 2+) (bpy-2,2′... more Two mononuclear ruthenium complexes [(bpy) 2 Ru II L 1 /L 2 ](ClO 4) 2 ([1] 2+ /[2] 2+) (bpy-2,2′ bipyridine, L 1 = 2,3-di(pyridin-2-yl)pyrazino[2,3-f ][1,10]phenanthroline) and L 2 = 2,3-di(thiophen-2-yl)pyrazino[2,3-f ][1,10]phenanthroline have been synthesized. The complexes have been characterized using various analytical techniques. The complex [1] 2+ has further been characterized by its single crystal X-ray structure suggesting ruthenium is coordinating through the N donors of phenanthroline end. Theoretical investigation suggests that the HOMOs of both complexes are composed of pyridine and pyrazine unit of ligands L 1 and L 2 whereas the LUMOs are formed by the contribution of bipyridine units. The low energy bands at ∼480 nm of the complexes can be assigned as MLCT with partial contribution from ligand transitions, whereas the rest are ligand centered. The complexes have shown Ru II /Ru III oxidation couples at E 1/2 at 1.26 (70 mV) V and 1.28 (62 mV) V for [1] 2+ and [2] 2+ vs Ag/AgCl, respectively, suggesting no significant role of distal thiophene or pyridine units of the ligands. The complexes are emissive and display solvent dependent emission properties. Both complexes have shown highest emission quantum yield and lifetime in DMSO (ϕ = 0.05 and τ avg = 460 ns and λ max em at 620 nm for [1] 2+ ; ϕ = 0.043 and τ avg = 425 ns and λ max em at 635 nm for [2] 2+). Further, the long luminescent lifetime of these complexes has been utilized to generate reactive oxygen species for efficient azo dye decomposition.
Physical Chemistry Chemical Physics, 2017
Enzymes are biological catalysts that can vastly accelerate the reaction rate of a substrate by a... more Enzymes are biological catalysts that can vastly accelerate the reaction rate of a substrate by accommodating it within the active site.