Spectroscopic and theoretical investigations on effective and selective complexation between porphyrins and fullerenes

Diels-Alder Reaction of C60 and C70 Fullerenes Confined in a Nanohoop: A Theoretical Study

The reactivity of the bonds in fullerenes is crucial for their chemical modification of their structures. Recent studies demonstrate that fullerenes can be encapsulated as guest molecule in conjugated [n]cyclodibenzopentalene nanohoop, forming intriguing host-guest systems with potential applications in organic material. In this study, the influence of encapsulating C60 and C70 fullerenes in a [4] cyclodibenzopentalene nanohoop on their bond reactivity is theoretically investigated. The binding energy of the complex of nanohoop and C60 is 2.7 kcal mol-1 higher than that of the nanohoop and C70, highlighting a substantial interaction. However, the differences in bond reactivity between encapsulated and isolated C60 and C70 is relatively small, due to interaction-induced effects from the nanohoop. To understand the origin of these observations, the distortion/interaction analysis was performed . These findings provide insight into how encapsulation affects fullerene reativity and contribute to the broader understanding of weak interactions in supramolecular systems. , The present study on fullerene-nanohoop host-guest system offers new insights into intermolecular weak interactions and enhances our understanding of structural and energetic aspects of molecular recognition and self-assembly in suppramolecular chemistry.

Recent Advances in Bonding Regulation of Metalloporphyrin-Modified Carbon-Based Catalysts for Accelerating Energy Electrocatalytic Applications

Metalloporphyrins modified carbon-based materials, owing to the excellent acid-base resistance, optimal electron transfer rates, and superior catalytic performance, have shown great potential in energy electrocatalysis. Recently, numerous efforts have concentrated on employing carbon-based substrates as platforms to anchor metalloporphyrins, thereby fabricating a diverse array of composite catalysts tailored for assorted electrocatalytic processes. However, the interplay through bonding regulation of metalloporphyrins with carbon materials and the resultant enhancement in catalyst performance remains inadequately elucidated. Gaining an in-depth comprehension of the synergistic interactions between metalloporphyrins and carbon-based materials within the realm of electrocatalysis is imperative for advancing the development of innovative composite catalysts. Herein, the review systematically classifies the binding modes (i.e., covalent grafting and non-covalent interactions) between carbon-based materials and metalloporphyrins, followed by a discussion on the structural characteristics and applications of metalloporphyrins supported on various carbon-based substrates, categorized according to their binding modes. Additionally, this review underscores the principal challenges and emerging opportunities for carbon-supported metalloporphyrin composite catalysts, offering both inspiration and methodological insights for researchers involved in the design and application of these advanced catalytic systems.

Photophysical insights into fullerene–porphyrazine supramolecular interactions in solution

This communication reports supramolecular interactions of a porphyrazine derivative, namely, 2,7,12,17-tetra-tert-butyl-5,10,15,20-tetraaza-21H,23H-porphine (1) with C₆₀ and C₇₀ in toluene and dichlorobenzene.

Physicochemical insights in non-covalent interaction of a newly designed triporphyrin with fullerenes C60 and C70 in solution

The present paper reports the synthesis of free-base (H(2)-1) and zinc-triporphyrins Zn-1, and their supramolecular complexes with C(60) and C(70) in toluene. While UV-Vis studies reveal ground state interaction between fullerenes and triporphyrins, steady state fluorescence measurements establish quenching of fluorescence of triporphyrins by fullerenes. Binding constants data evoke that Zn-1 may be employed as an efficient tweezers for C(70) in toluene. Time resolved emission studies establish relatively long-lived charge separated state for the C(70)/triporphyrin complexes. Molecular mechanics force field calculations in vacuo interpret the stability difference between C(60)/and C(70)/complexes of triporphyrin.

Spectroscopic and theoretical insights on determination of binding strength and molecular structure for the supramolecular complexes of a designed bisporphyrin with C60 and C70

The present article examines the binding affinity of the newly designed Zn2-bisporphyrin molecule, syn-1, towards C60 and C70 in toluene medium. The investigation is carried out by UV-vis spectrophotometric, steady state and time-resolved fluorescence spectroscopic techniques. The bisporphyrin, syn-1, serves as an effective and selective molecular tweezer for C70 as average value of binding constants (K) for the non-covalent complexes of syn-1 with C60 and C70 are estimated to be 1.65 × 104 and 1.05 × 105 dm3 · mol-1, respectively. Binding of C70 in the cleft of syn-1 is clearly demonstrated by the quantum chemical calculations at ab initio level of theory. Molecular electrostatic potential maps demonstrate significant redistribution of charges in these supramolecules. Proton NMR studies suggest that the C70 moiety remains at the shallow part of the cleft of syn-1.

Absorption spectrophotometric, fluorescence, transient absorption and quantum chemical investigations on fullerene/phthalocyanine supramolecular complexes

The present paper reports the photophysical investigations on supramolecular interaction of a phthalocyanine derivative, namely, 2,9,16,23-tetra-tert-butyl-29H,31H-Pc (1) with C(60) and C(70) in toluene. The binding constants of the C(60) and C(70) complexes of 1 are estimated to be 27,360 and 25,205 dm(3), respectively. Transient absorption measurements in the visible region establishes that energy transfer from C60*T (and C70*T) to 1 occurs predominantly in toluene which is subsequently confirmed by the consecutive appearance of the triplet states of 1. Quantum chemical calculations at DFT level of theory explore the geometry and electronic structure of the supramolecules and testify the significant redistribution of charge between fullerenes and 1.

Photophysical properties of a novel Ni(II)-diporphyrin in presence of fullerenes: insights from experimental and theoretical studies

The present paper highlights the photophysical aspects of the topologically new Ni(II)-diporphyrin (Ni(2)-1)/fullerene host-guest ensembles. Both absorption and fluorescence studies reveal that Ni(2)-1 undergoes efficient complexation with both C(60) and C(70) in toluene medium. In the fluorescence study, remarkable enhancement of the fluorescence intensity of Ni(2)-1 was observed by the addition of C(60), while normal quenching of fluorescence occurred in case of C(70). From the fluorescence and UV-vis studies, the binding constants of Ni(2)-1 with C(60) and C(70) were determined to be approximately 1.7 x 10(4) and approximately 2.7 x 10(4) dm(3) mol(-1), respectively. Ab initio theoretical calculations reveal that C(70)/Ni(2)-1 complex favor end-on orientation of C(70) rather than side-on approach.

Spectral and theoretical studies on effective and selective non-covalent interaction between tetrahexylporphyrins and fullerenes

The host-guest interaction of zinc(II) 5,10,15,20-tetrahexylporphyrin (Zn-THP) and its free base (H2-THP) with fullerenes (C60 and C70) has been studied in toluene medium. Binding constants (K) for H2- and Zn-THP complexes of fullerenes were determined by UV-vis, fluorescence and NMR spectroscopic techniques. Large K values of C70/THP complexes (KC70 ) were obtained in the range of 1.4-2.5 x 10(4)M(-1), while those of C60/THP complexes (KC60) were smaller (1.0-3.2 x10(3)M(-1)). These results show that the KC70 is about 10 times as large as KC60 in both THPs (KC70/KC60 = 10). Enthalpies of formation (DeltaHf degrees) for various fullerene/THP complexes were estimated by ab initio calculations; DeltaHf degrees for C60/H2-THP, C70/H2-THP, C60/Zn-THP and C70/Zn-THP complexes are 5.82, 2.80, 2.31 and 1.54 kcal mol(-1), respectively. The trends in DeltaHf degrees support the experimental results of selective complexation of THPs towards C70 over C60 and fullerenes towards Zn-THP over H2-THP.