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2. Fluoride ion receptors based on dipyrrolyl derivatives bearing electron-withdrawing groups: Synthesis, optical and electrochemical sensing, and computational studies

Author

Ghosh, Tamal, Maiya, Bhaskar G., and Ming Wha Wong

Subjects
Receptor antibodies -- Research, Intermolecular forces -- Research, Fluorides -- Atomic properties, Chemicals, plastics and rubber industries
Abstract

The underlying intermolecular interactions of the receptors anion complexes along with the insight into the structures, intrinsic binding affinities that supports the experimental characterization via computations of NMR and UV-visible spectra is studied. DFT calculations lend further support affinity and high selectivity of the fluoride ion for receptors.

Published
2004

8. Enhanced optical limiting and nonlinear absorption properties of azoarene-appended phosphorus (V) tetratolylporphyrins

Author

Kiran, P. Prem, Reddy, D. Raghunath, Maiya, Bhaskar G., Dharmadhikari, Aditya K., Kumar, G. Ravindra, and Desai, Narayana Rao

Subjects
Absorption of light -- Research, Porphyrins, Astronomy, Physics
Abstract

Optical limiting performance, third-order nonlinearity [[chi].sup.(3)], and nonlinear absorption properties have been investigated in a new class of azoarene phosphorus (V) porphyrins with charge transfer (CT) states. The introduction of axial azoarene groups into the phosphorus porphyrin structure is found to reduce the limiting threshold by a factor of 2 and lead to a rise in the second hyperpolarizability by 1 order of magnitude in the picosecond time regime and by 2 orders of magnitude in the nanosecond regime. The experimental data show reverse saturation of absorption in the nanosecond time regime and a saturation of the nonlinear absorption above a fluence of 0.5 J/[cm.sup.2] in the picosecond regime. The presence of the CT state reduces saturation of excited-state absorption (ESA) in the [S.sub.1] [right arrow] [S.sub.n] transition through the [S.sub.1] [right arrow] CT transition. Faster CT [right arrow] [T.sub.1] transition increases the ESA from [T.sub.1] [right arrow] [T.sub.n] states in the nanosecond regime. A self-consistent theoretical analysis based on rate equations is used to estimate the high-lying excited-state lifetimes and absorption cross sections from the experimental results. OCIS codes: 190.0190, 190.4360, 190.4710, 140.3360.

Published
2002

12. Abstracts

Author

Basu, J., Rohatgi-Mukherjee, K. K., Chatterjee, S., Sarkar, S., Bhattacharyya, S. N., Dasmahapatra, G. K., Wolff, Thomas, Von Bunau, Gunther, Dhawan, S. N., Sen, Dipankar, Bera, Subhash Ch, Gupta, S. C., Yadav, N. S., Sahu, Manabendra, Saha, Manjubikash, Masilamani, V., Sastikumar, D., Behera, Pradipta Kumar, Mishra, Ashok Kumar, Muthusamy, S., Ramakrishnan, V. T., Ramamurthy, P., Sampath, S., Narayan, R., Manickam, M. C. Durai, Srinivasan, C., Pitchumani, K., Roja, M., Rajagopal, S., Ray, Reba, Mukherjee, Samaresh, Samanta, A., Natarajan, E., Selvaraj, S., Natarajan, P., Talwar, S. S., Viswanathan, K., Natarajan, P., Dhathathreyan, Aruna, Dhathathreyan, K. S., Biswal, Basanti, Song, Pill-Soon, Das, S., Muneer, M., Haridas, A., Manilal, V. B., Jayakumar, R., Ramasami, T., Julliard, M., Chanon, M., Joshi, P. N., Biswal, U. C., Joshy, C. L., Purushothaman, E., Maiya, Bhaskar G., Ganesan, S., Nagarajan, B., Narayanan, V., Mohanty, Prasanna, Shubin, V., Murthy, S. D. S., Karapetyan, N. V., Ramaraj, R., Gobi, K. V., Sankareswari, V. Gomathi, Ranganayaki, S., Bahadur, K., Kumar, Sajal, Sonawane, H. R., Kulkarni, D. G., Ayyangar, N. R., Sukumar, N., Venkitachalam, T. V., Rao, A. S., Ali, S. I., Kaur, Harpal, Anbalagan, V., Srivastava, T. S., Kumar, Awadhesh, Chowdhury, P. K., Rao, K. V. S. Rama, Mittal, J. P., Balasubramanian, N., Balasubramanian, S., Dutt, G. B., Doraiswamy, S., Manna, Bidyut Kumar, Rohatgi-Mukherjee, K. K., Chandra, A., Bagchi, B., Arunachalam, S., Devadason, J. R., Dhanasekaran, T., Prabahar, K. Joseph, Mathew, Lizamma, Ramakrishnan, V., Rajaram, J., Rao, V. R. S., Narayanan, P., Pillai, V. N. Sivasankara, Priyadarsini, K. I., Rajendran, T., Palaniandavar, M., Kaneko, M., Kira, A., Sidhu, M. S., Chopra, Arti, Gill, Barinder, Baby, Thomas, and Nampoori, V. P. N.

Published
1992
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14. Abstracts of posters presented at the symposium

Author

Maiya, Bhaskar G., Chauhan, S. M. S., Bhyrappa, P., Krishnan, V., Bhardwaj, P. K., Sarkar, Sabyasachi, Pandeya, Krishna B., Mathur, Pavan, Chakravarty, Akhil R., Das, Birinchi K., Behere, Digambar V., Modi, Sandeep, Mitra, Samaresh, Modi, Sandeep, Behere, Digambar V., Mitra, Samaresh, Saxena, Anil, Modi, Sandeep, Behere, Digambar V., Mitra, S., Mazumdar, Shyamalava, Medhi, Okhil K., Mitra, Samaresh, Mazumdar, Shyamalava, Mitra, Samaresh, Madan, Anup, Modi, Sandeep, Saxena, Anil, Behere, Digamber V., Mitra, S., Pandiyan, T., Palaniandavar, M., Narayanan, K. L., Manohar, H., Ramaraj, R., Thomas, C. C., Rajagopal, S., Rajendra, T., Srinivasan, C., Ramamurthy, P., Roy, R., Saha, M. C., Panchanan, S., Roy, P. S., Balagopalakrishna, C., Rajasekharan, M. V., Agarwala, B. V., Hingorani, S., Gowda, G. A. Nagena, Ramaswamy, Y. S., Halesha, R., Gowda, N. M. N., Reddy, G. K. N., Saxena, G. C., Gupta, K. L., Srivastava, P., Gupta, V. D., Ray, M., Mukherjee, R. N., Mohanty, R. N., Dash, K. C., Kapoor, Ramesh, Yadav, S., Sood, V., Kapoor, P., Anand, B. N., Bains, R., Usha, Aggarwal, K., Garge, P., Chikate, R., Padhye, S., Savariault, J. M., De Loth, P., Tuchgues, J. P., Jain, V. K., Vaidya, M. A., Jain, S. C., Kumar, S. Kalyan, Singh, Harkesh B., Mangaonkar, K. M., Patkar, D. N., Jha, N. K., Sharma, Pankaj, Date, S. K., Deshpande, C. E., Sathaye, S. D., Deshpande, S. B., Potdar, H. S., Darshane, V. S., Dash, A. C., Nanda, R. K., Das, N. N., Gangopadhyay, S., Banerjee, P., Kulshreshtha, S. K., Zacharias, P. S., Arulsamy, N., Ramasami, T., Subramanian, V., Nair, B. U., Kanthimathi, M., Sundararajan, G., Shivasubramanian, V., Bhattacharya, R. G., Biswas, S., Armstrong, J., Holt, E. M., and Koley, A. P.

Published
1990
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16. Ultrafast intramolecular electronic energy-transfer dynamics in a bichromophoric molecule

Author

Mondal, Jahur A., Ramakrishna, G., Singh, Ajay K., Ghosh, Hirendra N., Maiya, Bhaskar G., Mariappan, M., Mukherjee, Tulsi, and Palit, Dipak K.

Subjects
Dynamics -- Research, Electron transport -- Research, Chemical synthesis -- Research, Chemicals, plastics and rubber industries
Abstract

Intramolecular electronic energy-transfer (intra-EET) dynamics are investigated in 2-(9-anthryl)-1H-imidazo [4,5-f] [1,10]-phenanthroline (AIP), a newly synthesized bichromophoric molecule by using the steady state and time resolved absorption and fluorescence spectroscopic techniques. In AIP anthracene (AN) and 1H-imidazo [4,5-f] [1,10]-phenanthroline (IP) molecules are directly linked to each other through a C-C sigma bond without any intervening molecular bridge.

Published
2004

17. Phosphorous(V) porphyrin-azoarene conjugates: synthesis, spectroscopy, cis-trans isomerization, and photoswitching function`

Author

Reddy, Raghunath D., Maiya, Bhaskar G., Cimas, Alvaro, Antonio, Largo, and Schaefer, Henry F. III

Subjects
Porphyrins -- Chemical properties, Phosphorus -- Chemical properties, Isomerization -- Research, Chemicals, plastics and rubber industries
Abstract

The successful demonstration of the photoswitching function by a prototype phosphorous (V) [P(V)] porphyrin-azobenzene system, the design, the synthesis, spectral characterization, and cis-trans isomerization is described. The occurrence of reversible cis-trans isomerization of the porpherene bound azorene subunits in the class of porphyrin-azoarene (P-A) conjugates, are clearly suggested by the observations.

Published
2003

31. Schiff bases of nickel(II), copper(II) prophyrins and dibenzo-18-crown-6-interspersed bis-metal porphyrins. Protonation studies

Author

Maiya, Bhaskar G and Krishnan, V

Subjects
Inorganic & Physical Chemistry
Abstract

Schid-base (SB) derivatives of Ni(II) and Cu(II) porphyrins endowed with various amine functions $(R-NH_2)$, n-butylamine, p-anisidine and m-nitroaniline have been prepared from corresponding formyl porphyrins. Protonation studies of these SB derivatives reveal a marked red shift of the optical absorption bands in the visible region relative to the unprotonated imines. The magnitude of the observed red shifts in the protonated derivatives, $(SBH^+)$ are found to depend on the electron-withdrawing or electron-donating nature of the R group of the amines. The results of the optical absorption, $^1H$ NMR, EPR, and cyclicovoltammetric studics are illustrative of the fact that protonation of the SB deriwatives results in a localized positive charge, $P-C(H) = _N^+$ (H)-R in the periphery of the porphyrin (p) system. The dibenzo-18-crown-6 interspersed bisporphyrin schiff bases have been prepared from trans $4,4^{\prime}$-diamino dibenzo-18-crown-6 and forrnyl porphyrins. The protonation of these SB derivatives is found to proceed in a concerted Cash&. The cation complexation studies by the crown ether entity in the hisporphyrin systems have been investigated using optical absorption, magnetic resonance and electrochemical methods. The redox characteristics of the protonated dimeric SB porphyrins reveal that the first oxidation step involves a two-electron transfer reaction. This is important in view of their possible usage in multielectron transfer reactions of biological and catalytic interest.

Published
1987

33. Ultrafast Intramolecular Electronic Energy-Transfer Dynamics in a Bichromophoric Molecule †.

Author

Mondal, Jahur A., Ramakrishna, G., Singh, Ajay K., Ghosh, Hirendra N., Mariappan, M., Maiya, Bhaskar G., Mukherjee, Tulsi, and Palit, Dipak K.

Abstract

Intramolecular electronic energy-transfer (intra-EET) dynamics has been investigated in 2-(9-anthryl)-1H-imidazo [4,5-f] [1,10]-phenanthroline (AIP), a newly synthesized bichromophoric molecule, using the steady-state and time-resolved absorption and fluorescence spectroscopic techniques. In AIP, anthracene (AN) and 1H-imidazo [4,5-f] [1,10]-phenanthroline (IP) molecules are directly linked to each other through a C−C σ bond and without any intervening molecular bridge. Two constituent chromophoric moieties of this bichromophoric molecule interact relatively weakly in the ground state. In the excited singlet state, however, the AN moiety transfers its excitation energy quantitatively (the efficiency of energy transfer, φEET, is near unity) and rapidly (the rate of energy transfer, kEET, is 1.8 × 1011 s-1 in methanol) to the unexcited IP moiety. kEET decreases linearly with increase in viscosity of the solvents, and the process is significantly retarded in rigid glass matrixes. These observations suggest that, for an efficient EET process, the molecule needs to attain a conformational geometry, which is different from that of the ground state, by undergoing a conformational relaxation process following photoexcitation. The theoretically calculated energy-transfer rate (5.1 × 109 s-1) due to the Förster dipole−dipole-induced resonance-interaction mechanism is about 2 orders of magnitude smaller than the experimentally determined energy-transfer rate. Hence, the Dexter through-space exchange-interaction mechanism, which becomes predominant at shorter interchromophoric separation (R ∼ 6.3 Å in AIP) and requires specific conformation for efficient orbital overlap, should have the major contribution to the intra-EET process in AIP. Viscosity dependence of kEET suggests that we possibly measure the rate of the conformational relaxation process using the intra-EET process as the probe. [ABSTRACT FROM AUTHOR]

Published
2004
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