Photophysical Investigations on Determination of Ionicity and Electronic Structures for the Non-covalent Complexes of Calix[4]resorcinarene with Fullerenes C60 and C70 in the Solution State

Autor: Amal Halder, Sumanta Bhattacharya, Dulal C. Mukherjee
Rok vydání: 2010
Předmět:
Zdroj: Journal of Solution Chemistry. 39:1327-1340
ISSN: 1572-8927
0095-9782
Popis: Ground state non-covalent interactions between a macrocyclic receptor, C-methylcalix[4]resorcinarene (1) and fullerenes (C60 and C70) have been studied in benzonitrile by an absorption spectrophotometric method. Absorption bands are located in the visible region due to the charge transfer (CT) transition between 1 and various electron acceptors (including fullerenes), namely, 2,3-dichloro-5,6-dicyano-p-benzoquinone, tetracyanoquinodimethane and p-chloranil. Utilizing the CT absorption bands, various important physicochemical parameters, including oscillator strength, resonance energy, transition dipole strength of all the acceptor-1 complexes and vertical ionization potential of 1 are determined. Job’s method of continuous variation reveals 1:1 stoichiometry between fullerenes and 1. The most fascinating feature of the present study is that 1 binds selectively to C70 compared to C60 as obtained from binding constant (K) data of C60-1 (\(K_{\mathrm{C}60\mbox{-}\mathbf{1}}\)) and C70-1 (\(K_{\mathrm{C}70\mbox{-}\mathbf{1}}\)) complexes, i.e., \(K_{\mathrm{C}60\mbox{-}\mathbf{1}}=190\) dm3⋅mol−1 and \(K_{\mathrm{C}70\mbox{-}\mathbf{1}}=5{,}800\) dm3⋅mol−1 and selectivity (KC70-1/KC60-1) ∼30. Quantum chemical calculations based on hybrid density functional theory estimate the enthalpies of formation of the fullerene-1 complexes in vacuo and provide very good support for selectivity in the K values of the C70 and C60 complexes of 1. The exchange and correlation energies have been calculated using a hybrid DFT functional method. We have opted to use the hybrid DFT functional over the Hartree-Fock method, as it can account for correlation effects also. Molecular electrostatic potential map calculations give a clear picture on the electronic structures of the fullerene-1 complexes.
Databáze: OpenAIRE
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