@article {49326, title = {Far-red active unsymmetrical squaraine dyes containing N-arylated indoline donors for dye sensitized solar cells}, journal = {Photochemistry and Photobiology}, volume = {100}, year = {2024}, month = {JUL}, pages = {1116-1126}, type = {Article}, abstract = {

Squaraine dyes possess sharp far-red active transition with high extinction coefficient and form aggregates on TiO2 surface. Aggregation of dyes on TiO2 has been considered as a detrimental factor for DSSC device performance, which can be controlled by appending alkyl groups to the dye structures. Hence by integrating alkylated (alkyl groups with both in-plane and out-of-plane) aryl group with indoline moiety to make it compatible with other electrolytes and for controlling the dye-aggregation, a series of squaraine acceptor-based dyes SQA4-6 have been designed and synthesized. SQA4-6 dyes showed absorption between 642 and 653 nm (lambda max), photophysical and electrochemical studies indicated that the HOMO energy levels of this sets of dyes are well aligned with the potentials of I-/I3-\$\$ {\textbackslashmathrm{I}}_3\<\^\>{-} \$\$ and [Co(bpy)3]2+/3+ redox shuttles for better dye regeneration process. DSSC device efficiency of 3\% has been achieved for SQA5 dye with iodolyte (I-/I3-\$\$ {\textbackslashmathrm{I}}_3\<\^\>{-} \$\$) electrolyte in the presence of 0.3 mM of chenodeoxycholic acid (CDCA). The IPCE profile of DSSC device fabricated with SQA4-6 dyes indicated the contribution of aggregated structures for the photocurrent generation. Dye-sensitized solar cell (DSSC) device efficiency of 3\% (Jsc 5.72 mA cm-2, Voc 662 mV and ff 79\%) has been achieved for an unsymmetrical squaraine dye, SQA5 with iodolyte electrolyte and the incident photon to current efficiency (IPCE) profile indicates the contribution of aggregated structures for the photocurrent generation.*image

}, keywords = {aggregation of dye, arylation on N-atom of indoline donor, dye-sensitized solar cell, squaraine dye}, issn = {0031-8655}, doi = {10.1111/php.13907}, author = {Jadhav, Avinash P. and Singh, Ambarish Kumar and Pandya, Rinu and Vanka, Kumar and Krishnamoorthy, Kothandam and Jayaraj, Nithyanandhan} } @article {49347, title = {Unravelling polymorphism-driven luminescence in GFP chromophore analogues: insights into the phase transition and morphology-dependent optical waveguide properties}, journal = {Journal of Materials Chemistry C}, volume = {12}, year = {2024}, month = {JUN }, pages = {8368-8379}, type = {Article}, abstract = {

The advent of multi-emission organic solid-state materials in response to external stimuli has sparked the scientific community due to their potential application in developing sophisticated optoelectronic sensors and bioanalytical tools. This article presents green fluorescent protein chromophore (GFPc) analogue-based polymorphs exhibiting significantly different emissions due to various noncovalent interactions in the supramolecular environment and conformational alterations in the crystalline state. In both compounds (A and B), the polymorphs undergo monotropic thermal phase transitions that are characterized by DSC, HSM, and VT-PXRD techniques. The distinct fluorescent emission characteristics of these polymorphs demonstrated morphology-related optical waveguiding features. Specifically, the plate-type Form A1 emitted light with a 2D blue hue, while the needle-type Form A2 emitted light with a yellowish-green colour. Additionally, the impressive waveguiding capabilities of Form B1 were explored in both straight and singly/doubly bending configurations to facilitate fluorescence propagation. Consequently, there is significant interest in developing organic materials based on GFP chromophores, which exhibit low emission in solution but display multi-fluorescent emission in the solid state. These materials are promising for applications such as optoelectronic devices, security tags, live cell imaging, and fluorescent inks. Polymorphs of GFPc analogs A and B display differences in their optical waveguiding properties in 1D and 2D depending on the crystal shapes. Furthermore, Form B1 demonstrates efficient optical waveguiding capabilities even when the crystal is bent.

}, issn = {2050-7526}, doi = {10.1039/d3tc04676a}, author = {Dabke, Niteen B. and Raut, Yash and Mali, Bhupendra P. and Pandya, Rinu and Vanka, Kumar and Manoj, Kochunnoonny and Gonnade, Rajesh G.} } @article {49381, title = {Unravelling the prebiotic origins of the simplest α-ketoacids in cometary ices: a computational investigation}, journal = {CHEMICAL COMMUNICATIONS}, volume = {60}, year = {2024}, month = {OCT }, pages = {11283-11286}, type = {Journal Article}, keywords = {GLYOXYLATE, Hydrocarbons, Metabolism, Precursors}, issn = {1359-7345}, doi = {10.1039/d4cc03074e}, author = {Dash, Soumya Ranjan and Pandya, Rinu and Singh, Geetika and Sharma, Himanshu and Das, Tamal and Haldar, Hritwik and Hotha, Srinivas and Vanka, Kumar} } @article {49887, title = {Cocrystals of the green fluorescence protein chromophore analogue: coformer-induced switch between AIE and ACQ}, journal = {Crystal Growth \& Design}, volume = {25}, year = {2025}, month = {SEP}, pages = {7473-7488}, type = {Article}, abstract = {

Fluorescent organic solids hold great potential for advancing photonics applications. However, tuning their solid-state photoluminescent emissions remains a significant challenge. In this study, we report the synthesis and characterization of five cocrystals (two cocrystal polymorphs) derived from a pristine imidazolinone derivative (A) and the various coformer molecules, namely 1,2,4,5-tetrafluoro-3,6-diiodobenzene, 1,2,4,5-tetrafluoro-3,6-dibromobenzene, perfluoronaphthalene, and 3,4,5-trifluorobenzoic acid. The structural and optical properties of these cocrystals were examined by using single-crystal X-ray diffraction, absorption spectroscopy, photoluminescence spectroscopy, and photoluminescence decay spectroscopy. Cocrystals I, II, and III are isomorphous pairs and exhibit three-dimensional isostructurality, where the coformer molecules bridge adjacent helices of compound A, leading to aggregation-induced emission. In contrast, the cocrystal polymorphs IVA and IVB developed using coformer 3,4,5-trifluorobenzoic acid form two-dimensional sheet-like structures mediated by pi-stacking interactions between the coformers and molecule A, with interplanar distances ranging from 3.2 to 3.5 \& Aring;. These stronger pi-pi interactions promote nonradiative decay pathways, resulting in reduced or quenched fluorescence and an aggregation-caused quenching effect. To gain further insights into their electronic properties, theoretical analysis including frontier molecular orbitals, time-dependent density functional theory, Hirshfeld surface analysis, molecular electrostatic potential, and noncovalent interaction plots were performed.

}, issn = {1528-7483}, doi = {10.1021/acs.cgd.5c00559}, author = {Suresh, Sneha and Dabke, Niteen B. and Pandya, Rinu and Vanka, Kumar and Dutta, Madhusudan and Gonnade, Rajesh G.} } @article {49614, title = {Double anchoring squaraine dye with triazatruxene amine donor for dye-sensitized solar cells: sequential cosensitization for panchromatic light-harvesting}, journal = {Journal of Photochemistry and Photobiology A-Chemistry}, volume = {462}, year = {2025}, month = {MAY}, pages = {116229}, type = {Article}, abstract = {

Dyes are firmly bound to a semiconducting TiO2 film using carboxylic acid anchoring groups for an efficient electron transfer from the excited state of dye to the conduction band (CB) of TiO2. Strong dye binding can be accomplished with multi-anchoring dye designs to improve photophysical characteristics, including high extinction coefficients, panchromatic absorption, post-sensitization modifications, and dark current suppression, besides enhancing the stability of the dye-TiO2 interface. Herein, a novel KV2D dye with double squaraine acceptor and double carboxylic acid anchoring groups is designed to achieve a high extinction coefficient (epsilon, 3.57 x 105M-1cm-1) and robust binding to the TiO2 film for an effective electron transfer. We systematically changed the amount of coadsorbent chenodeoxycholic acid (CDCA) to control the aggregation of dyes on the TiO2 surface that improves the power conversion efficiency (PCE, eta) for the devices based on the doubleanchoring KV2D. Out of these devices, KV2D: CDCA (1:10) based cell exhibited the best PCE of 5.26\% with VOC of 754 mV, JSC of 10.41 mA/cm2, and ff of 67\%. The sequential cosensitization studies were carried out with a far-red active dye to find the effect of the strong binding of the sensitizer to the TiO2 film. Interestingly, when di-anchoring, KV2D was sensitized first for 12 h and then sequentially cosensitized with far-red absorbing SQS4 for 5 h to achieve a PCE of 5.0\% with VOC of 697 mV, JSC of 10.23 mA/cm2, and ff of 70\% with panchromatic spectral response in IPCE upto 730 nm giving higher photocurrent generation.

}, keywords = {aggregation of dyes, Bulky donor unit, Double acceptor dye, Dye-sensitized solar cells, self-assembly of dye, squaraine dyes, triazatruxene}, issn = {1010-6030}, doi = {10.1016/j.jphotochem.2024.116229}, author = {Ingole, Kiran Balaso and Siby, Jesna and Pandya, Rinu and Vanka, Kumar and Krishnamoorthy, Kothandam and Nithyanandhan, Jayaraj} } @article {49552, title = {Investigating the visible range photoresponse of an organic single-crystal analogue of the green fluorescent protein}, journal = {Nanoscale}, volume = {17}, year = {2025}, month = {APR}, pages = {8614-8623}, type = {Article}, abstract = {

The growing demand for lightweight, flexible, semi-transparent and low-cost photodetectors (PDs) in wearable electronics and optical communication systems has prompted studies to investigate organic materials as feasible alternatives to conventional inorganic PDs. However, modern organic PDs often face responsivity, detectivity, and photoresponse speed limitations, particularly in the visible range. Here, we present the photoresponse of an organic single-crystal analogue of the green fluorescent protein (GFP) chromophore photodetector, fabricated on a silicon nitride substrate. A significant increase in photocurrent was detected upon illumination with visible wavelengths (532 nm, 630 nm, and halogen light). A remarkably consistent and repeatable photoresponse was obtained during the ON and OFF illumination cycles. The device showed the dependence of photocurrent on the applied bias voltages. The measured photocurrent, responsivity, detectivity, rise time, decay time, noise equivalent power and external quantum efficiency are studied for different wavelengths. Strikingly, the fabricated device demonstrates excellent performance in the visible region compared to several conventional organic and inorganic PDs. The observed responsivity and detectivity values for the device are 98 mA W-1 and 7.94 x 108 Jones, respectively. Furthermore, the device also exhibits rapid photoresponse dynamics with a rise time of 180 ms and a decay time of 152 ms. The excellent photodetection features indicate that the single crystal GFP could serve as a versatile broadband material for future applications in optoelectronics.

}, issn = {2040-3364}, doi = {10.1039/d4nr05252h}, author = {Virole, Vishal and Dabke, Niteen and Verma, Sahil and Kumar, Ajay and Pandya, Rinu and Husale, Sudhir and Vanka, Kumar and Gonnade, Rajesh and Kanawade, Rajesh} } @article {49704, title = {Manganese(i)-catalyzed dehydrogenative borylation of terminal alkynes}, journal = {Dalton Transactions}, volume = {54}, year = {2025}, month = {JUL}, pages = {10426-10432}, type = {Article}, abstract = {

Compounds containing carbon-boron bonds serve as valuable intermediates for constructing more complex molecules by transforming these bonds into other carbon-element bonds. The catalytic dehydrogenative borylation of carbon-hydrogen bonds using HBpin presents an appealing method for synthesizing carbon-boron bonds. While this approach has been extensively explored with noble metals for various types of carbon-hydrogen bonds, its application with manganese-based catalysts remains rare. This study explores a dehydrogenative borylation process employing an Earth-abundant transition metal catalyst, FcbpyMn(CO)3Br (Mn(i)), in combination with HBpin under mild conditions. Arylalkynes featuring electron-withdrawing, electron-donating, and heteroaryl substituents yielded good to excellent results. Thorough DFT calculations were performed to understand the mechanism.

}, issn = {1477-9226}, doi = {10.1039/d5dt00577a}, author = {Ghanwat, Pratiksha B. and Bora, Debashree and Pandya, Rinu and Vanka, Kumar and Saha, Biswajit and Sen, Sakya S.} } @article {49599, title = {Unlocking thermodynamic enolate for kinetically controlled desymmetrizing vinylogous (4+1) carbospiroannulation}, journal = {Chemistry-A European Journal}, volume = {31}, year = {2025}, month = {MAY}, type = {Article}, abstract = {

An unprecedented thermodynamically unfavorable (4+1) deysmmetrizing spiroannulation through a thermodynamic enolate intermediate, enabling a single-step synthesis of ubiquitous scaffolds such as all-carbon chiral spirocycles, is disclosed. In this spiroannulation, we present a vinylogous organocatalytic enantioselective desymmetrizing (4+1) cycloaddition approach involving alkylidene malononitrile and cyclopent-1,3-dienone. This carbospiroannulation method produces functionally enriched spiro[4,4]nonane structures with three stereocenters, has presented good-to-high yields and enantiomeric ratios. Detailed DFT calculations reveal an intriguing reaction mechanism, which validates our observations.

}, keywords = {3-diones, alkylidene malononitrile, cyclopent-1, quaternary stereocenters, spiro compounds, thermodynamic enolate}, issn = {0947-6539}, doi = {10.1002/chem.202500671}, author = {Singh, Sanjay and Singh, Abhijeet and Pandya, Rinu and Vanka, Kumar and Singh, Ravi P.} } @article {49824, title = {Visible-light active π-extended unsymmetrical squaraine dyes for dye-sensitized solar cells: steric effects for controlling the aggregation of dyes}, journal = {ACS Applied Energy Materials}, volume = {8}, year = {2025}, month = {OCT}, pages = {15459-15470}, type = {Article}, abstract = {

The dye-anchored TiO2 photoanode plays a vital role in the light harvesting and charge separation processes in dye-sensitized solar cells. Aggregation of dyes (H- and J-type) on the TiO2 surface is a facile process due to the presence of a periodical dye anchoring sites on the exposed facet of titania, and such self-assembled dye structures help broadening the absorption profile. However, photocurrent generation from such aggregated structure is a challenging task in dye-sensitized solar cell devices. Hence, controlling the dye aggregation on the TiO2 surface is an important aspect. Controlling the aggregation of dyes by which (i) an enhanced photocurrent generation (J SC) and (ii) enhanced V OC can be achieved by including the steric factors to the dye design principles, the steric factor in the sensitizer may help passivate the TiO2 surface to avoid the charge recombination process between electrons present in TiO2 and the oxidized electrolyte. On the other hand, extension of pi-conjugation in a sensitizer helps enhance the light absorption in the visible region besides modulating the HOMO and LUMO energy levels. Hence, synergizing both pi-extensions along with features that control the dye aggregation has been considered in designing visible active squaraine dyes. A thiophene pi-spacer was inserted in between a visible-light active unsymmetrical squaraine unit and a cyanoacetic acid acceptor unit to provide the AJ1 and AJ2 dyes. Though both the dye molecules possess a similar pi-framework, the AJ2 dye was functionalized with both in-plane and out-of-plane alkyl groups to decrease the aggregation of dyes on the TiO2 surface compared to AJ1. The AJ1 and AJ2 dyes absorbed at 560 nm with shoulder peaks appeared at 528 nm, which can be assigned to vibronic progression (1082 cm-1), and additional characteristic peaks of thiophene appeared at 392 nm with the molar extinction coefficient of 1.16-1.19 x 105 M-1 cm-1 in CH3CN. The LUMO and HOMO energy levels are well aligned with the conduction band of TiO2 and the redox potential of iodolyte (I-/I3 -) electrolyte with sufficient overpotentials for charge injection and dye regeneration processes, respectively. The highest DSSC device efficiency of 7.37\% (J SC 14.44 mA/cm2, V OC 0.771 V, ff 67.1\%) was achieved for the AJ2 dye with iodolyte (I-/I3 -) electrolyte in the presence of 2 equiv of optically transparent coadsorbent chenodeoxycholic acid (CDCA), which showed a good IPCE response in between 400 and 700 nm. Further, cosensitization of visible-light active AJ1, AJ2, and SQA10 dyes with a complementary far-red active SQS4 dyes showed the device efficiencies of 5.53\% (AJ1:SQS4:CDCA), 7.14\% (AJ2:SQS4:CDCA), and 7.18\% (SQA10:SQS4:CDCA) with a good IPCE response in the 400-720 nm region.

}, keywords = {cosensitization, Dye aggregation, Dye-sensitized solar cells, pi-extended squaraine dye, visible-lightactivedyes}, issn = {2574-0962}, doi = {10.1021/acsaem.5c02553}, author = {Jadhav, Avinash P. and Siby, Jesna and Pandya, Rinu and Vanka, Kumar and Krishnamoorthy, Kothandam and Nithyanandhan, Jayaraj} } @article {49788, title = {Auxiliary triazatruxene donor-based squaraine dyes for dye-sensitized solar cells: cis- and trans- configuration of dyes for modulating photophysical and electronic properties}, journal = {Chemistry-an Asian Journal}, volume = {21}, year = {2026}, month = {JAN}, type = {Article}, abstract = {

In DSSCs, dye regeneration efficiency and dye aggregation on the TiO2 surface can be modulated by using bulky aromatic donors wrapped with alkyl groups. Introduction of rigid aromatic rings around the donor unit of a dye will directly impact the driving force for electron injection and dye regeneration of a dye. In this work, we designed and synthesized KNS dyes with an auxiliary TAT donor integrated with a visible active squaraine dye. Here, octupolar-structured auxiliary TAT wrapped with alkyl groups is used as a strong donor and shelter to reduce the dye aggregation and charge recombination process. Further, to improve the light-harvesting efficiency and incident photon-to-current conversion efficiency of DSSC devices fabricated with KNS dyes, the central squaric acid unit has been modified by appending the electron-withdrawing dicyano group at the central squaric unit, and the trans-configured KNS1 dye was converted to cis-configured KNS2 dye. The power conversion efficiency of devices based on the KNS dyes was studied with and without 3 equivalents of CDCA by using the I-/I3 - electrolyte. Out of these devices, the KNS1: CDCA (1:3) based cell exhibited the best PCE of 6.25\% with V OC of 793 mV, J SC of 11.08 mA cm-2, and ff of 71\%.

}, keywords = {Bulky donor unit, Dye-sensitized solar cells, self-assembly of dye, squaraine dyes, triazatruxene}, issn = {1861-4728}, doi = {10.1002/asia.70455}, author = {Ingole, Kiran Balaso and Siby, Jesna and Pandya, Rinu and Vanka, Kumar and Krishnamoorthy, Kothandam and Nithyanandhan, Jayaraj} } @article {49954, title = {Photoluminescence decay lifetime study of hydrothermally synthesized highly porous ruthenium-silica composite for optical dissolved oxygen sensing application}, journal = {ACS Applied Nano Materials}, volume = {9}, year = {2026}, month = {JAN}, pages = {937-949}, type = {Article}, abstract = {

Pore size and surface area of photoluminescence (PL)-based transition metal composites play crucial roles in facilitating oxygen diffusion, thereby enhancing the response and sensitivity of optical dissolved oxygen (DO) sensors. In this study, we successfully applied the hydrothermal method to synthesize a porous ruthenium composite embedded in a silica matrix, demonstrating its effectiveness for optical DO sensing applications. The ruthenium-silica (Ru-Si) composites were synthesized using Ru(bpy)3 2+ and tetraethyl orthosilicate (TEOS) as precursors, with reaction temperatures ranging from 120 degrees C to 200 degrees C over a fixed duration of 4 h. The structural, morphological, and compositional characterization techniques confirmed the successful synthesis and evaluated the porosity, surface features, and chemical structure of the resulting composites. The optimized Ru-Si composite exhibited the highest porosity, characterized by a specific surface area of 996.78 m2 g- 1, and exhibited the highest decay lifetime of 8.14 mu s in deionized (DI) water, compared to other composites. Importantly, we demonstrate an excellent linear response of the synthesized Ru-Si composite to DO concentrations ranging from 2.58 to 11.16 mg L-1, with a Stern-Volmer constant of 0.12. Furthermore, a density functional theory study was conducted to investigate the electronic transitions and to elucidate the oxygen quenching mechanism of the excited Ru composite with molecular oxygen. The calculated photophysical parameters of the composite show good agreement with the experimental results. Preliminary results suggest that the synthesized Ru-Si with high pore size and surface area could be an efficient and effective composite for use in DO sensing applications.

}, keywords = {Hydrothermal method, opticalDO sensor, oxygen quenching, photoluminescent, ruthenium composite}, doi = {10.1021/acsanm.5c04307}, author = {Hattale, Gangadhar and Kadam, Rutuja and Virole, Vishal and Pandya, Rinu and Paul, Aditya and Kumar, Ajay and Shevate, Rahul and Vanka, Kumar and Saha, Avishek and Kanawade, Rajesh} }