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Item Enhancing charge mobilities in organic semiconductors by selective fluorination: A design approach based on a quantum mechanical perspective(Royal Society of Chemistry, 2017-08-14) Maiti, Buddhadev; Schubert, Alexander; Sarkar, Sunandan; Wang, Kunlun; Li, Zhe; Geva, Eitan; Twieg, Robert J.; Dunietz, Barry D.Selective fluorination of organic semiconducting molecules is proposed as a means to achieving enhanced hole mobility. Naphthalene is examined here as a root molecular system with fluorination performed at various sites. Our quantum chemical calculations show that selective fluorination can enhance attractive intermolecular interactions while reducing charge trapping. Those observations suggest a design principle whereby fluorination is utilized for achieving high charge mobilities in the crystalline form. The utility of this design principle is demonstrated through an application to perylene, which is an important building block of organic semiconducting materials. We also show that a quantum mechanical perspective of nuclear degrees of freedom is crucial for a reliable description of charge transport. © 2017 The Royal Society of Chemistry.Item Enhancing fluorescence and lowering the optical gap through C[dbnd]P doping of a π-conjugated molecular backbone: A computational-based design approach(Elsevier B.V., 2021-11-20) Sarkar, Sunandan; Durairaj, Pandiselvi; Protasiewicz, John D.; Dunietz, Barry D.Design principles of organic fluorescent materials are investigated at the molecular level using a first-principles-based computational approach. The design approach incorporates hetero atoms into a conjugated cyclic skeleton by introducing C[dbnd]P bonds. In particular we report the design of a molecular system of an extended conjugation system that maintains its planarity across the full system, achieving low lying electronic excited states of large oscillator strengths. We also present calculations that confirm the competing process of internal system crossing to be too slow for affecting the actual relaxation following photexcitation. © 2021 The Author(s)Item Luminescent 1H-1,3-benzazaphospholes(Royal Society of Chemistry, 2022-12-22) Evariste, Sloane; Harrison, Alexandra M.; Sarkar, Sunandan; Rheingold, Arnold L.; Dunietz, Barry D.; Heinicke, Joachim W.; Delgado Rosario, Emalyn; Yoon, Sungwoon; Teets, Thomas S.; Protasiewicz, John D.2-R-1H-1,3-Benzazaphospholes (R-BAPs) are an interesting class of σ2P heterocycles containing P = C bonds. While closely related 2-R-1,3-benzoxaphospholes (R-BOPs) have been shown to be highly photoluminescent materials depending on specific R substituents, photoluminescence of R-BAPs has been previously limited to an example having a fused carbazole ring system. Here we detail the synthesis and structural characterization of a new R-BAP (3c, R = 2,2′-dithiophene), and compare its photoluminescence against two previously reported R-BAPs (3a, R, R′ = Me and 3b, R = 2-thiophene). The significant fluorescence displayed by the thiophene derivatives 3b (φ = 0.53) and 3c (φ = 0.12) stands in contrast to the weakly emissive methyl substituted analogue 3a (φ = 0.08). Comparative computational investigations of 3a-c offer insights into the interplay between structure-function relationships affecting excited state relaxation processes. © 2023 The Royal Society of Chemistry.Item Real-time visualization of latent fingermarks with level 3 details based on a solid state emissive organic fluorophore using the powder dusting method(Royal Society of Chemistry, 2023-12-11) Shabashini, Arivalagan; Richard, Sathiaraj; Panda, Manas K; Panja, Sumit K; Nandi, Ganesh ChandraHerein, we have designed and synthesized a water-soluble organic fluorescent probe (Py-Pr-OH, 3) and applied it for latent fingermarks (LFMs) detection via the powder dusting method. The probe is highly emissive (in the solid state) and amphiphilic in nature with preferred lipophilicity. The pyridyl cation attached to the polar end group enhances its water solubility. The single crystal structure and packing analysis reveals that the absence of π-π stacking interaction in the lattice contributes to the strong solid-state fluorescence of the Py-Pr-OH molecule. LFM images with level 1-3 details (including, ridge pattern, ridge width, ridge size and sweat pore size) on various substrates have been identified with high resolution and low background interference. The LFMs have been developed very quickly (<10 s), and clear pictures with multilevel details are obtained via simple mobile phone photography. The electrostatic interactions between the probe with sebaceous rich FMs enhance the LFM imaging with high contrast, sensitivity, accuracy, and low background interference. Most importantly, details of the fingermark ridge width and the sweat pores are analyzed under SEM. © 2024 RSC.Item Crystal structure of 3-[(E)-(2-hydroxy-3-methoxybenzylidene)amino]-1-methyl-1-phenylthiourea(International Union of Crystallography, 2016-04-05) Gangadharan, Rajeswari; Muralisankar, Mathiyan; Sreekanth, Anandaram; Rahman, Abdullakutty Anees; Sethusankar, KIn the asymmetric unit of the title compound, C16H17N3O2S, there are two independent molecules (A and B), which show an E conformation with respect to the C=N bond. An intramolecular O - H⋯N hydrogen bond with an S(6) motif stabilizes the molecular structure. The terminal phenyl and benzene rings are almost orthogonal to each other, the dihedral angle being 87.47(13)° for molecule A and 89.86(17)° for molecule B. In the crystal, weak bifurcated N - H⋯(O,O) hydrogen bonds link the two independent molecules, forming a supramolecular chain with a C 2 1(14)[R 2 1(5)] motif along the b axis. A weak C - H⋯O interaction is also observed in the chain. © 2016.Item Thiophene anchored two new sets of carbohydrazide for the chemosensing and biological investigation(Elsevier B.V., 2023-01-17) Mary Mathew, Merlin; Valappil Rasin, Puthiya; Mandal, Priyabrata; Sreekanth, AnandaramThe presence of hazardous metal ions or anions in industrial and domestic water may adversely affect the living systems there. Hence their detection is reducing the risk to human and environmental systems. In this study, we investigate the spectroscopical variations of different analytes and the biological performance of two derivatives of carbohydrazide scaffolds. So, we developed two chemosensors 3TCH and BTTCH to detect Cu2+ and F− in an aqueous medium by using photoluminescence spectroscopy (PL). The BTTCH has also sensitively detected the AcO−. Spectral maxima deviations and colour changes in the concentration in concern can serve as indicators of the interaction that was produced. The limit of detection (LOD) was calculated for all the complexes, which all are in lower limits of quantification and the complex 3TCH + F− showed a much lower value of 8.23 × 10−8 M. The binding constants are calculated using the Benesi-Hildebrand equation, 3TCH + F− showed the highest value (K = 9.39 × 10−7M−1) of the association constant, indicating the highest affinity. Additionally, it was investigated whether the chemosensors could be used with common household items like mouthwash and vinegar. © 2023Item Host-guest interactions of coumarin-based 1,2-pyrazole using analytical and computational methods: Paper strip-based detection, live cell imaging, logic gates and keypad lock applications(Elsevier Ltd, 2024-01-05) Rasin, Puthiyavalappil; Basheer, Sabeel M; Haribabu, Jebiti; Aneesrahman, K.N.; Vadakkedathu Palakkeezhillam, Vishnunarayanan Namboothiri; Bhuvanesh, Nattamai; Echeverria, Cesar; Santibanez, Juan F; Sreekanth, AnandaramA novel Coumarin-based 1,2-pyrazole, HCPyTSC is synthesised and characterized. The chemosensor has been shown to have efficient colourimetric and fluorescence sensing capabilities for the quick and selective detection of fluoride and copper ions. At 376 and 430 nm, the HCPyTSC exhibits selective sensing for Cu2+ and F− ions. By examining the natural bond orbital (NBO) analysis and the potential energy curve (PES) of the ground state for the function of the C–H bond, it has been determined from the theoretical study at hand that the deprotonation was taken from the ‘CH’ proton of the pyrazole ring. For F− and Cu2+, the HCPyTSC detection limits were 4.62 nM and 15.36 nM, respectively. Similarly, the binding constants (Kb) for F− and Cu2+ ions in acetonitrile medium were found to be 2.06 × 105 M−1 and 1.88 × 105 M−1. Chemosensor HCPyTSC with and without F− and Cu2+ ions have an emission and absorption response that can imitate a variety of logic gates, including the AND, XOR, and OR gates. Additionally, a paper-based sensor strip with the HCPyTSC was created for use in practical, flexible F− sensing applications. The paper-based sensor was more effective in detecting F− than other anions. The effectiveness of HCPyTSC for the selective detection of F− in living cells as well as its cell permeability were examined using live-cell imaging in T24 cells. © 2024Item 2-Phenyl-5,7-bis(prop-2-en-1-yloxy)-4H-chromen-4-one(International Union of Crystallography, 2008-12-03) Nallasivam, Angannan; Nethaji, Munirathinam; Vembu, Nagarajan; Ragunathan, Venkatraman; Sulochana, NagarajanIn the title compound, C21H18O4, tthe dihedral angle between the chromene ring system and the pendant phenyl ring is 6.1 (1)°. The crystal structure is stabilized by an intermolecular C - H⋯O and C - H⋯π inter-actions.Item 5,7-Bis(benz-yloxy)-2-phenyl-4H-chromen-4-one(International Union of Crystallography, 2008-11-29) Nallasivam, Angannan; Nethaji, Munirathinam; Vembu, Nagarajan; Jaswant, Buckle; Sulochana, NagarajanIn the title compound, C29H22O4, the chromene ring is almost planar with a small puckering [0.143 (2) Å]. The crystal structure is stabilized by C - H⋯O and C - H⋯π inter-actions. Edge-to-face (centroid-centroid distances of 3.894 and 3.673 Å) and face-to-face (centroid-centroid distance of 3.460 Å) π-π-ring electron inter-actions are also observed. © 2008.Item Dimethyl 2,2′-[(4-oxo-2-phenyl-4H-chromene-5,7-diyl)dioxy]diacetate: A more densely packed polymorph(International Union of Crystallography, 2009-01-14) Nallasivam, Angannan; Nethaji, Munirathinam; Vembu, Nagarajan; Jaswant, Buckle; Sulochana, NagarajanThe title mol-ecule, C21H18O8, crystallizes in two crystal polymorphs, see also Nallasivam, Nethaji, Vembu & Jaswant [Acta Cryst. (2009), E65, o314-o315]. The mol-ecules of both polymorphs differ by the conformation of the oxomethyl-acetate groups. The title mol-ecules are rather planar compared to the mol-ecules of the other polymorph. In the title mol-ecule, one of the oxomethyl-acetate groups is disordered (occupancies of 0.6058/0.3942). The structures of both polymorphs are stabilized by C - H⋯O and C - H⋯π inter-actions. Due to the planarity of the title mol-ecules and similar inter-molecular inter-actions, the title mol-ecules are more densely packed than those of the other polymorph.Item 5,7-Dimeth-oxy-2-phenyl-4H-chromen-4-one(International Union of Crystallography, 2009-02-11) Nallasivam, Angannan; Nethaji, Munirathinam; Vembu, Nagarajan; Ragunathan, Venkatraman; Sulochana, NagarajanThe asymmetric unit of the title compound, C17H 14O4, contains two independent mol-ecules which differ in the relative orientations of the phenyl rings with repect to the essentially planar [maximum deviations of 0.029 (2) and 0.050 (2) Å in the two mol-ecules] chromene fused-ring system, forming dihedral angles of 10.3 (5) and 30.86 (5)° in the two mol-ecules. The crystal structure is stabilized by weak C - H⋯O and C - -H⋯π inter-actions, and π-π stacking inter-actions.Item 6,8-Dibromo-5-hydr-oxy-4-oxo-2-phenyl-4H-chromen-7-yl acetate(International Union of Crystallography, 2009-02-21) Nallasivam, Angannan; Nethaji, Munirathinam; Vembu, Nagarajan; Ragunathan, Venkatraman; Sulochana, NagarajanIn the title compound, C17H10Br2O5, the chromene ring is almost planar with minimal puckering [total puckering amplitude = 0.067 (4) Å]. The dihedral angle between chromeme ring system and phenyl ring is 3.7 (2)°. The crystal structure is stabilized by intermolecular C - H⋯O inter-actions and an intramolecular O - H⋯O hydrogen bond also occurs.Item Naphthalimide based smart sensor for CN-/Fe3+ and H2S. Synthesis and application in RAW264.7 cells and zebrafish imaging(Royal Society of Chemistry, 2020-02-28) Naha, Sanay; Wu, Shu-Pao; Velmathi, SivanAchieving selective detection of target analytes in aqueous media continues to be an arduous proposition. Herein, we report the conceptualization and synthesis of a novel tailor-fit molecular probe R based on 1,8-naphthalimide which acts as a trifunctional molecular sensor for CN-, Fe3+ and H2S. R shows colorimetric and fluorometric "on-off" relay recognition for CN- (red colour and orange emission) and Fe3+ (no colour and no emission) in 5% H2O + DMSO medium which is experimentally ascertained to be a tandem deprotonation-protonation process and is supported by 1H-NMR titration. Among all RSS (Reactive Sulphur Species), R shows selectivity for H2S through red colouration. Other coexistent anions, cations and RSS cause no discernible perturbation to the detection process. The detection of H2S is attributed to a chemodosimetric reduction of the nitro to amino group as evidenced by a potentiometric titration assay. The experimental observations are well supported by DFT theoretical calculation. The Ka for CN-/Fe3+ are 1.4 × 104 M-1, 6.07 × 104 M-1 respectively and photochemical yield of R + CN- is 0.86. Limit of detections for CN-, Fe3+ and H2S are 17.5 nM, 8.69 μM and 8.1 μM respectively. Receptor R is effective for real time applications, bio-compatible and has been successfully employed for confocal fluorescence imaging of RAW264.7 cell and zebrafish. This journal is © 2020 The Royal Society of Chemistry.Item Sulfated magnesium zirconate catalyzed synthesis, antimicrobial, antioxidant, anti-inflammatory, and anticancer activity of benzo[d]thiazole-hydrazone analogues and its molecular docking(Elsevier B.V., 2021-09-20) Govindaiah, Shivaraja; Naha, Sanay; Madhuchakrapani Rao, Tadimety; Revanasiddappa B.C.; Srinivasa, Sudhanva M.; Parashuram, L; Velmathi, Sivan; Sreenivasa, SwamyA comprehensive demonstration of novel catalytic synthetic pathway using sulfated zirconia (solid acid catalyst) to generate a library of bioactive compounds precisely, the benzo[d]thiazole-hydrazone derivatives (4a-n). The compounds are characterized using ubiquitous spectroscopic techniques such as, IR, 1H and 13C NMR, HR-Mass. The set of molecules are screened in vitro biological activities namely, antimicrobial, antioxidant, anti-inflammatory and anticancer which are aptly supported by the molecular docking studies. Among the compounds, 4a and 4e are observed to be the most potent antibacterial agents where as 4a and 4c displayed significant antifungal activity. On the contrary, compounds 4e and 4j showed good antioxidant properties and 4b and 4j exhibited excellent anti-inflammatory activity. The compound 4d found to be a potent anti-cancer agent against tested human cancer cell lines MIAPaca2, HeLa, A549, and HCT116 (IC50 values of 19.09 ± 0.50, 19.93 ± 0.25, 7.76 ± 0.50, and 5.05 ± 0.25 μM respectively). Molecular docking studies were performed using DNA Gyrase, N-myristoyltransferase, COX-2, EGFR, HER2, and VEGFR2 proteins. Notably, compound 4d strongly binds to receptors EGFR and HER2 as inferred by their binding energies compared to standard inhibitors Gefitinib (EFGR), Lapatinib (EGFR), Afatinib (HER2), and Canertinib (HER2). © 2021Item One-pot three-component synthesis of novel phenyl-pyrano-thiazol-2-one derivatives and their anti-diabetic activity studies(Elsevier B.V., 2022-07-12) Prabhakaran, Srinivasan; Nivetha, Narayanasamy; Patil, Shashank M.; Mary Martiz, Reshma; Ramu, Ramith; Sreenivasa, Swamy c; Velmathi, SivanAn easy and rapid synthetic approach for the synthesis of phenyl-pyrano-thiazol-2-one derivatives using base catalysed one-pot three-component reaction between substituted aromatic aldehyde, N-methyl-1-(methylthio)-2-nitroethamine (NMSM) and thiazolidinedione is reported. Among the bases tested, piperidine was proven to be the most efficient organo-base catalyst, when ethanol was used as a solvent. The product was obtained in good yields and confirmed using FT-IR, NMR and mass spectroscopic techniques. The electron withdrawing group substituted product was obtained in higher yield compared to the electron donating group substituted product. The strategy used involved mild reaction conditions, shorter reaction time and easy isolation of products. The reaction sequence involved Knoevenagel condensation, Michael addition followed by intramolecular O-cyclization. © 2022 The AuthorsItem Synthesis and characterization of Piperine amide analogues: Their In-silico and invitro analysis as potential antibacterial agents(Elsevire B.V., 2022-05-16) Sivashanugam, Arthi; Vemathi, SivanPiperine, a natural product obtained from black pepper was structurally modified and a set of 15 piperic amide analogues were synthesized. The molecules were analysed for their ADME properties and binding energy potentials with anti-bacterial target proteins and only the structures that were drug-like were carried forward to synthesis. Then the theoretically potent synthesized analogues were subjected to in-vitro anti-bacterial assay against five bacterial strains, Escherichia coli, Acinetobacter baumannii, Staphylococcus aureus, Escherichia faecalis, and Staphylococcus epidermidis. It was noted that the analogues exceeded the activity of piperine at tested concentration. Of all the analogues, trimethyl piperic amide analogue (PA-1) and p-nitro piperic amide analogue (PA-14) has worked exceptionally well against all the strains employed. The mechanism of action of the molecules could be correlated to sulfanamide drugs since the molecular docking results with DHPS protein show correlation with experimental results. The overall ranking of the susceptibility of the tested strains goes as follows, S. epidermidis > S. aureus = A. baumannii > E. faecalis > E. coli. © 2022 The Author(s)Item Benzodioxole grafted spirooxindole pyrrolidinyl derivatives: synthesis, characterization, molecular docking and anti-diabetic activit(Royal Society of Chemistry, 2022-08-25) Nivetha, Narayanasamy; Martiz, Reshma Mary; Patil, Shashank M.; Ramu, Ramith; Sreenivasa, Swamy; Sivan, VelmathiA highly stereoselective, three-component method has been developed to synthesize pyrrolidine and pyrrolizidine containing spirooxindole derivatives. The interaction between the dipolarophile α,β-unsaturated carbonyl compounds and the dipole azomethine ylide formed in situ by the reaction of 1,2-dicarbonyl compounds and secondary amino acids is referred to as the 1,3-dipolar cycloaddition reaction. The reaction conditions were optimized to achieve excellent stereo- and regioselectivity. Shorter reaction time, simple work-up and excellent yields are the salient features of the present approach. Various spectroscopic methods and single crystal X-ray diffraction examinations of one example of compound 6i validated the stereochemistry of the expected products. The anti-diabetic activity of the newly synthesized spirooxindole derivatives was tested against the α-glucosidase and α-amylase enzymes. Compound 6i was found to exhibit potent inhibition activity against α-glucosidase and α-amylase enzymes which is further evidenced by molecular docking studies. © 2022 The Royal Society of Chemistry.Item New spirooxindole pyrrolidine/pyrrolizidine analogs: design, synthesis, and evaluation as an anticancer agent(Royal Society of Chemistry, 2025-05-19) Nivetha, Narayanasamy; Venkatesan, Janarthanan; Murugan, Dhanashree; Rangasamy, Loganathan; Wu, Shu Pao; Velmathi, SivanA novel series of mesitylene-based spirooxindoles were synthesized via the multicomponent [3 + 2] cycloaddition reaction in a greener medium. Spectroscopic techniques such as 1H and 13C NMR and HRMS analysis were carried out for the structural elucidation of all the spirooxindole derivatives. The in vitro cytotoxicity properties of spirooxindole analogs 4/5(a-g) against the human lung (A549) cancer cell line exhibited encouraging outcomes. Of the fourteen synthesized spirooxindole analogs, seven compounds (4a, 4b, 4e, 4g, 5c, 5e, and 5f) showed greater potency towards the A549 lung cancer cell line. The cytotoxicity of the spirooxindole analogs was also investigated against a non-cancerous mouse embryonic fibroblast NIH-3T3 cell line. Compounds 5e and 5f, which exhibited better cytotoxic effect against the cancerous A549 cells (3.48 and 1.2 μM), appeared to be non-cytotoxic against the non-cancerous mouse embryonic fibroblast. Studies using Hoechst and acridine orange/ethidium bromide staining also demonstrated the apoptotic effect of the potent compounds, which decreased cell proliferation. © 2025 The Royal Society of Chemistry.Item An isophorone-derived AIE-active probe for peroxynitrite detection and bioimaging applications(Royal Society of Chemistry, 2025-07-11) Lalitha, Raguraman; Vivek, Vishnu Halnor; Lu, Yueh-Hsun; Wu, Shu Pao; Velmathi, SivanCompounds exhibiting aggregation-induced emission (AIE) are remarkable due to their characteristic restriction of intramolecular rotation, making them highly versatile for a wide range of applications. Herein, an isophorone based probe (IHP) was developed for the detection of peroxynitrite (ONOO−) using the C 00000000 00000000 00000000 00000000 11111111 00000000 11111111 00000000 00000000 00000000 N as the reactive group. Photophysical investigations were conducted to explore the aggregation behaviour of IHP in two different solvent systems: DMSO:PBS and DMSO. In DMSO, only the monomeric form of the dye was observed, showing no unusual behaviour. However, in DMSO : PBS (1 : 1), multiple emitting species were detected, indicating the coexistence of dye aggregates and monomers. The fluorescence spectra exhibited wavelength-dependent changes, with the aggregates displaying a red-shift compared to the monomers, indicating J-aggregation. The AIE properties of IHP resulted in red emission, with a fluorescence response towards ONOO− through oxidative cleavage of the C N bond to an aldehyde accompanied by the shift in emission maximum. Under physiological conditions, the probe exhibited good selectivity and high sensitivity to ONOO−, low detection limit of 1.1 μM and rapid recognition within 200 seconds. Furthermore, the probe was effectively used to image exogenous and endogenous peroxynitrite in living cells. © 2025 The Royal Society of Chemistry.Item Radical cascade cyclization of amino acid-tethered 1,6-enynones with sulfonyl hydrazides for N-terminal modification: synthesis of functionalized succinimide derivatives(Royal Society of Chemistry, 2025-08-01) Sivanantham, Mathiyazhagan; Jacob Stanley, Jenis; Muthu, Kesavan; Velmathi, Sivan; Senadi, Gopal Chandru; Senadi, Gopal Chandru; Ramasamy, MohankumarA metal-free strategy for the N-terminal cyclization of amino acids has been developed by synthesizing highly functionalized succinimide derivatives through radical cyclization of amino acid-tethered 1,6-enynones with sulfonyl hydrazide using NIS and H2O2 as an oxidant. The notable advantages of this work includes time-efficient, good E/Z ratio, moderate to good yields, and was synthesized on a gram-scale. Furthermore, the synthetic utility of the product 5aa was performed by (i) Suzuki coupling reaction with iodo-functionality; and (ii) dipeptide formation using glycine methyl ester. © 2025 The Royal Society of Chemistry.