Density Functional Theory based study on structural, vibrational and NMR properties of cis - trans fulleropyrrolidine mono-adducts (original) (raw)
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Chemical Physics Letters, 2000
Optimized geometries and 13 C NMR chemical shifts of fullerene C 80 have been calculated by density functional theory using B3LYP/6-31G* for all isolated-pentagon-rule isomers with non-zero HOMO±LOMO gap (isomers 1, 2, 3, 4 and 5). D 2 distorted isomer 7 is predicted as ®rst-order saddle-point by B3LYP/STO-3G. The calculated NMR spectrum of isomer 2 agrees well with experiment of Hennrich, con®rming the assignment unequivocally. The predicted spectra of other isomers either show unusually large spectral span or have unusual chemical shifts for some sites, indicating unfavorable electron distribution. Both energetic and NMR properties indicate these isomers are less stable than isomer 2. Ó (M. Kertesz). 0009-2614/00/$ -see front matter Ó 2000 Elsevier Science B.V. PII: S 0 0 0 9 -2 6 1 4 ( 0 0 ) 0 0 9 6 9 -6
Theoretical study of bis-adduct fulleropyrrolidines isomers
Revue Roumaine de Chimie, 2019
A detailed theoretical investigation of bis-adduct fulleropyrrolidines was developed in our work. All the possible isomers of our molecule were determined. Corresponding structures were optimized, their energies were calculated and their stability was discussed using the density functional theory method. The theoretical calculation carried out in our work shows that the trans and equatorial structures of the bis adduct are the most stable structures among the eight different possible isomers. The LUMO energy calculated for the bis adduct shows that it is higher than the LUMO of C60 and the LUMO of the mono adduct calculated at the same level. This suggests that this compound can be used efficiently as electron acceptor in photovoltaic cell application.
Spectroscopic Analyses of Modified Fulleropyrrolidine Derivatives
The Open Spectroscopy Journal, 2015
Fullerene (C 60) is enhanced with pyrrolidine group to produce fulleropyrrolidine which is considered as one of the most important derivatives of fullerene. Fulleropyrrolidine is further modified in order to enhance its solubility which in turn could enhance its biological applications. Accordingly this work is dedicated to modify fulleropyrrolidine carbodithioic acid as NO 2 group introduced at meta position. Quantitative structure-activity relationship models (QSAR) was utilized to evaluate the biological activates of the investigated compounds through some descriptors. Later on chalcogenide could be subtitled in order to form three derivative groups. The QSAR descriptors were compared with the QSAR of the parent compound. Results indicate that, NO 2 group enhances the biological activity.
European Journal of Organic Chemistry, 2011
Inductive and mesomeric effects of the [60]fulleropyrrolidine (Pyr=C 60) and the [60]fullerene (C 60) molecular frameworks have been investigated by linear free energy relationship analyses. The electronic effects of these moieties have been studied by expressly designing [60]fulleropyrrolidine derivative 1, which has a C-H bond α to both a carbonyl group (C-H α) and a C 60 cage. The extent of polarization of such a bond was then used to probe electron-withdrawing perturbation induced by the fullerene sphere. Thermodynamic measurements based on both theoretical and experimental approaches allowed the acidity of ketone 1 to be measured; this resulted in about a 1 ϫ 10 6-fold increase in acidity with respect to that of the structurally correlated acetophenone. Experimental and theoretical kinetic determinations were used [a] Dipartimento di Chimica e Tecnologie del Farmaco,
Structural and electronic properties of pyrrolidine-functionalized [60] fullerenes
We have investigated energetic, geometric, electronic, and field emission properties of three recently synthesized fulleropyrrolidines based on the density functional theory method B3LYP/6-31G(d). Fulleropyrrolidines show higher conductivity, and solubility in water, and smaller work function in comparison with the pristine C 60 fullerene. The functionalization of C 60 with different pyrrolidines containing -NH 2 , NO, or NO 2 groups transforms it to an n-type semiconductor. The functionalization can also dramatically enhance the electrophilicity of the C 60 about 23-37%. Moreover, it should be mentioned that the work function is mainly influenced by the pyrrolidine containing -NO 2 group whereas the conductivity is largely affected by the one containing -NH 2 functionality.
Vibrational spectroscopic and structural investigations on fullerene: A DFT approach
2016
Highlights • Conformational analysis was carried out for the monomer and dimer forms of Gly-Tyr dipeptide. o The observed vibrational frequencies were assigned and compared with the calculated frequencies. • The effects of intermolecular hydrogen bonding on the geometry and the wavenumbers were determined. o HOMO-LUMO energies revealed occurrence of charge transfer within the molecule.
Molecular Physics, 2014
Density functional theory calculations were performed on C 82 hydroxylated fullerene. B3LYP and PBE0 functionals with 6-31G** basis set were utilised to get chemical shieldings, chemical shifts and the isotropic Fermi contact coupling on each atomic site. A relation between nuclear magnetic resonance (NMR) properties and reactivity of the molecule, obtained through the electronic Fukui function, was observed. Interestingly, the most stable configurations of OH groups adsorbed on C 82 surface were obtained when the hydroxyl groups are adsorbed on deshielded (isotropically and anisotropically) sites. For open-shell systems, a relation between isotropic Fermi contact, spin density and average Fukui function was found, that is, sites with a great amount of Fukui function (analytical and the one obtained through finite difference) and spin density have the largest isotropic Fermi contact coupling data. With the adsorption of the first hydroxyl molecules, spin densities and Fukui functions show preferential sites to adsorb the following OH groups close to previously adsorbed. Additionally, theoretical spectra of chemical shifts of C 82 (OH) n (n = 1, 2, 3 and 4) were obtained and they were compared with experimental reports, getting a reasonable comparison. For example, regarding 13 C NMR chemical shifts obtained in C 82 OH molecule, 80 ppm (B3LYP) and 79 ppm (PBE0) were calculated on hydroxylated carbon, which is in good agreement with experimental results in C 60 fullerols.
Physica B: Condensed Matter, 2018
The most stable, optimized structures of fullerene (C) and bromofullerenes (C 60 Br 6) molecules were predicted by the density functional theory calculations using B3LYP method with 6311G(d,p) basis set. The obtained parameters were estimated by density functional theory (DFT) and time-dependent density functional theory (TD-DFT). Bromofullerene (C 60 Br 6) was architectured by directly bonding with bromine atom at C 60 reactive sites. Theoretically calculated vibrational wavenumbers were assigned and compared. Ultraviolet-visible spectrum was mimicked by Polarizable Continuum model. The 13C NMR spectra were simulated by nuclear magnetic tensor GIAO for C 60 and C 60 Br 6 relative to tetramethyl silane. The molecular electrostatic potential surface was simulated. The transition between highest occupied molecular orbital (HOMO) and lowest unoccupied molecular orbital (LUMO) revealed different charge transfer possibilities which occur for the molecule and other related molecular properties were computed and tabulated. Natural bond orbital (NBO) analysis was carried out to image the charge transfer between the localized bonds and lone pairs of the electrons. The enhanced reactivity and peculiar energy gap by the substitution of bromine in fullerene pave way for designing the optoelectronic devices and bioactive molecules which will be useful in the field of sensors and carbon nano medicine.
The Journal of Physical Chemistry A, 2001
Optimized geometries and 13 C NMR chemical shifts of fullerene C 82 have been calculated by density functional theory at the B3LYP/6-31G* level for all isolated-pentagon-rule (IPR) isomers with nonvanishing HOMO-LOMO gap (isomers 1, 2, 3, 4, 5, and 6). The calculated 13 C NMR spectrum of isomer 3 agrees well with the experimental spectrum of the C 2 isomer, while the predicted spectra of isomers 1 and 5 differ significantly from experiment. Thus, the observed isomer is unambiguously assigned to C 82 :3 isomer for the first time. Both the energetic and NMR properties show that isomers 2 and 4 might be observable.