Faculty Publications
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Item Ultrafast nonlinear optical properties of dye-doped PMMA discs irradiated by 40 fs laser pulses(2009) Xia, Y.; Jiang, Y.; Fan, R.; Dong, Z.; Zhao, W.; Chen, D.; Umesh, G.The two-photon absorption (TPA) characteristics of PMMA discs doped with three different dyes were studied using an fs-pulsed Ti-Sapphire laser as the pump source, and employing the open-aperture Z-scan technique. TPA cross-sections obtained for PMMA doped with the dyes PM597, DCM and rhodamine 6G-rhodamine B (co-doped) were found to be equal to 24.7, 33.3 and 32.3 GM, respectively (1 GM=10-50 cm4 s phot-1 mol-1). Furthermore, two-photon fluorescence was measured for the samples containing DCM and rhodamine 6G-rhodamine B (co-doped). Compared to the one-photon fluorescence spectrum, the peaks in the two-photon fluorescence spectrum were red shifted and the extent of red shift increased with increasing doping concentration. We have also observed that the red shift in the two-photon fluorescence peak of the samples in the solid form is much larger than that in the solution state. This phenomenon could be explained by a twisted intra-molecular charge transfer model. © 2009 Elsevier Ltd. All rights reserved.Item Meso-tris(2-furyl/2-thienyl) substituted porphyrin-ferrocene ‘click’ conjugates: synthesis, experimental, and computational studies(Royal Society of Chemistry, 2024) Shet, S.N.; Patil, M.; Shetti, V.S.The chemical synthesis of 5-(4-azidophenyl)-10,15,20-tris(2-furyl/2-thienyl)porphyrins and their utilization in a Cu(i) catalyzed alkyne-azide ‘click’ reaction (CuAAC) with ethynylferrocene to obtain the hitherto unknown meso-tris(2-furyl/2-thienyl) substituted porphyrin-ferrocene ‘click’ conjugates are reported. These new ‘click’ conjugates were studied along with the reference ‘click’ conjugates containing all-meso-aryl substituted porphyrins by experimental and computational methods. Compared to the reference, the new conjugates displayed red-shifted absorption/emission bands, easier porphyrin ring reduction, and an efficient photoinduced electron transfer (PET) process from ferrocene to a porphyrin unit. Density functional theory (DFT) calculations performed on these conjugates revealed a good correlation with the experimental results. © 2024 The Royal Society of Chemistry.Item Porphyrin-azoheteroarenes: synthesis, photophysical, and computational studies(Royal Society of Chemistry, 2025) Shet, S.N.; Bhat, V.G.; Swathi, S.G.; Udayakumar, U.; Shetti, V.S.Azobenzenes (Ph-N = N-Ph) are well-known photochromic compounds with widespread applications. Replacing one or both phenyl rings of azobenzenes with heteroarenes leads to a new class of compounds known as azoheteroarenes (Het-N N-Ph/Het). Azoheteroarenes have gained attention as promising alternatives to traditional azobenzenes in the field of photopharmacology due to their ability to undergo photoswitching under visible light. Interestingly, the chemistry of porphyrin-containing azoheteroarenes has been underexplored. In this study, we present the synthesis of hitherto unknown hybrid molecules: porphyrin-azopyrroles (porphyrin-N N-pyrrole) and porphyrin-azoindoles (porphyrin-N N-indole), which also feature porphyrins with five-membered meso-substituents, such as 2-furyl and 2-thienyl groups. The porphyrin-azoheteroarenes with meso-tris(2-furyl/2-thienyl) substitutions demonstrate red-shifted absorption and emission bands, more significant Stokes shifts, and smaller optical bandgaps compared to hybrids containing only meso-aryl groups. Additionally, these porphyrin-azoheteroarenes exhibit higher fluorescence emission intensities than their corresponding precursor porphyrins. © 2025 The Royal Society of Chemistry.