Investigations on photophysical properties and binding strength for the supramolecular complexes of newly designed diporphyrins with fullerenes

Mukherjee, Sibayan; Bauri, A. K.; Bhattacharya, Sumanta

doi:10.1016/j.molstruc.2009.11.046

Cited by 14 publications

(5 citation statements)

References 29 publications

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“…Both theoretical and experimental observations envisage that such a binding motif of C 70 toward 1 takes place to maximize the π−π interactions. This feature also suggests that, like C 70 −porphyrin interaction, , the presence of dispersive forces associated with π−π interactions is playing the key role in our present investigations. One important point to mention here is that the approach of fullerene guests toward calix[4]pyrrole host takes place from the side containing the −NH group of 1 (see Table ).…”

Section: Resultssupporting

confidence: 61%

Spectroscopic and Theoretical Insights into the Origin of Fullerene−Calix[4]pyrrole Interaction

et al. 2010

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The present paper reports, for the first time, supramolecular interaction of meso-octamethyl calix[4]pyrrole (1) with fullerenes C(60) and C(70) in solutions having varying polarity (e.g., toluene, 1,2-dichlorobenzene and benzonitrile and chloroform). The interaction is facilitated through charge transfer (CT) transition as evidenced from well-defined CT absorption bands in the visible region of absorption spectroscopy. Utilizing the CT transition energy for the complexes of 1 with various electron acceptors, we have determined the ionization potential of 1. Estimation of degrees of CT, oscillator, and transition dipole strengths suggest that the complexes are almost of neutral character in ground state. Higher magnitude of electronic coupling element value for the C(70)-1 complex compared to C(60)-1 indicates strong binding between C(70) and 1. Binding constants (K) of the fullerene-1 complexes have been determined from UV-vis investigations, which indicate high selectivity of 1 toward C(70). Extraordinary large K value of the C(70)-1 complex in chloroform medium (K approximately 1.43 x 10(6) dm(3) x mol(-1)) establishes that a polar environment facilitates such interaction. Both proton NMR and liquid IR studies provide very good support in favor of strong binding between C(70) and 1. (13)C NMR study proves that C(70) binds 1 with its equatorial belt, which substantiates the role of pi-pi interaction behind such strong interaction (i.e., high K value). Semiempirical theoretical calculations at the third parametric level (PM3) explore the stability difference between C(60)- and C(70)-1 complexes. PM3 calculations also reveal that approach of C(70) toward 1 is directed in side-on manner rather than in a conventional end-on alignment.

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Section: Resultssupporting

confidence: 61%

Spectroscopic and Theoretical Insights into the Origin of Fullerene−Calix[4]pyrrole Interaction

et al. 2010

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“…Thus, C 70 / 1 complex gains ∼1.935 kJ·mol −1 of extra stabilization energy when it approaches the cavity of 1 in a side-on manner rather than in its end-on orientation. It is already well established that in fullerene/porphyrin complexes, the 6:6 ring-juncture bond of the C 70 , rather than 6:5 ring-juncture bond, lies closest to the porphyrin plane, − as the 6:6 “double” bonds of C 70 are more electron-rich than 6:5 “single” bonds. Thus, in our present work, the equatorial face of C 70 is centered over the electropositive center of the Pc plane, which can be viewed as an enhancement in van der Waals interaction due to availability of greater surface area favoring strong π−π interactions.…”

Section: Resultsmentioning

confidence: 99%

Spectroscopic and Theoretical Investigations on Effective and Selective Interaction of Fullerenes C₆₀ and C₇₀ with a Derivatized Zn−phthalocyanine: Stabilization of Charge-Recombined State by Side-On Approach of C₇₀

et al. 2010

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The photophysical aspects of noncovalently linked fullerenes C(60) and C(70) with a designed metallophthalocyanine, namely, zinc-2,3,9,10,16,17,23,24-octakis-(octyloxy)-29H,31H-phthalocyanine (1) have been investigated employing various spectroscopic tools such as UV-vis absorption spectrophotometry, steady state and time-resolved fluorescence, along with solution state IR measurements in toluene medium. The ground state interaction between fullerenes and 1 is first evidenced from UV-vis measurements. Binding constants (K) for the complexes of C(60) and C(70) with 1 are determined to be 13,235 and 27,670 dm(3) x mol(-1), respectively. Steady state fluorescence experiment reveals efficient quenching of the excited singlet state of 1 in presence of both C(60) and C(70). Emission studies reveal K values of 8945 and 19,175 dm(3) x mol(-1) for C(60)/1 and C(70)/1 complexes, respectively. The magnitude of K suggests that 1 preferentially binds C(70) in comparison to C(60) as average selectivity in K of C(70) over C(60) is enumerated to be 2.0. Time resolved emission measurements establish that C(70)/1 complex is stabilized much more in comparison to C(60)/1 complex in terms of charge recombination. Liquid IR studies provide very good support in favor of ground state complexation between fullerenes and 1. Molecular mechanics calculations at force field model and semiempirical calculations employing third parametric method substantiate the strong binding between C(70) and 1, and at the same time, determine the orientation of bound guest (here C(70)) within the cavity of 1.

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“…Table 2. It is already well established that in fullerene-porphyrin complexes, the 6:6 ring-juncture bond of the C 70 , rather than 6:5 ring-juncture bond, lies closest to the porphyrin plane [72][73][74] as the 6:6 "double" bonds of C 70 are more electron-rich than 6:5 "single" bonds. Thus, in our present work, the equatorial face of C 70 is centered over the electropositive center of the ZnPc plane which may be viewed as a spontaneous enhancement in van der Waals interaction due to availability of greater amount of volume (V) and surface area (A) favoring strong -interactions.…”

Section: Binding Constants and Theoretical Calculationsmentioning

confidence: 99%

Photophysical and theoretical insights on non-covalently linked fullerene–zinc phthalocyanine complexes

Ray¹,

Chattopadhyay²,

Bhattacharya³

2011

Spectrochimica Acta Part A: Molecular and Biomolecular Spectros

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Investigations on photophysical properties and binding strength for the supramolecular complexes of newly designed diporphyrins with fullerenes

Cited by 14 publications

References 29 publications

Spectroscopic and Theoretical Insights into the Origin of Fullerene−Calix[4]pyrrole Interaction

Spectroscopic and Theoretical Insights into the Origin of Fullerene−Calix[4]pyrrole Interaction

Spectroscopic and Theoretical Investigations on Effective and Selective Interaction of Fullerenes C₆₀ and C₇₀ with a Derivatized Zn−phthalocyanine: Stabilization of Charge-Recombined State by Side-On Approach of C₇₀

Photophysical and theoretical insights on non-covalently linked fullerene–zinc phthalocyanine complexes

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Investigations on photophysical properties and binding strength for the supramolecular complexes of newly designed diporphyrins with fullerenes

Cited by 14 publications

References 29 publications

Spectroscopic and Theoretical Insights into the Origin of Fullerene−Calix[4]pyrrole Interaction

Spectroscopic and Theoretical Insights into the Origin of Fullerene−Calix[4]pyrrole Interaction

Spectroscopic and Theoretical Investigations on Effective and Selective Interaction of Fullerenes C60 and C70 with a Derivatized Zn−phthalocyanine: Stabilization of Charge-Recombined State by Side-On Approach of C70

Photophysical and theoretical insights on non-covalently linked fullerene–zinc phthalocyanine complexes

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Spectroscopic and Theoretical Investigations on Effective and Selective Interaction of Fullerenes C₆₀ and C₇₀ with a Derivatized Zn−phthalocyanine: Stabilization of Charge-Recombined State by Side-On Approach of C₇₀