CNDO/S calculations of magnetic circular dichroism of polyacenes

Obbink, J.H.; Hezemans, Alfons M. F.

doi:10.1016/0009-2614(77)80696-9

Cited by 11 publications

(5 citation statements)

References 21 publications

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“…33 The electric transition moments m were calculated with the dipole velocity operator method and the magnetic transition moments m with the complete angular momentum operator method. 34…”

Section: Complex Structure and CD Calculationsmentioning

confidence: 99%

Stereoselective interaction of ketoprofen enantiomers with β-cyclodextrin: ground state binding and photochemistry

Marconi

Mezzina

Manet

et al. 2011

Photochem Photobiol Sci

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The chiral recognition ability of β-cyclodextrin (β-CyD) vs.S- and R-ketoprofen (KP) enantiomers has been studied by circular dichroism (CD), isothermal titration calorimetry (ITC) and NMR. The association constants of the 1 : 1 complexes obtained from CD and ITC titration experiments resulted to be the same for both enantiomers within the experimental uncertainty. Well differentiated CD spectra were determined for the diastereomeric complexes. Their structure was assessed by molecular mechanics and molecular dynamics calculations combined with quantum mechanical calculation of the induced rotational strengths in the low energy KP:β-CyD associates, upon comparison of the calculated quantities with the corresponding experimental CD. The inclusion geometry is similar for both enantiomers with the aromatic carbonyl inserted in the CyD cavity, the monosubstituted ring close to the primary CyD rim and the carboxylate group exposed to the solvent close to the secondary rim. NMR spectra fully confirmed the geometry of the diastereomeric complexes. Tiny structural differences were sensibly probed by CD and confirmed by 2D ROESY spectra. Photoproduct studies with UV absorption and MS detection as well as nanosecond laser flash photolysis evidenced lack of chiral discrimination in the photodecarboxylation of KP within the cavity and formation of a photoaddition product to β-CyD by secondary photochemistry of 3-ethylbenzophenone.

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“…33 The electric transition moments m were calculated with the dipole velocity operator method and the magnetic transition moments m with the complete angular momentum operator method. 34…”

Section: Complex Structure and CD Calculationsmentioning

confidence: 99%

Stereoselective interaction of ketoprofen enantiomers with β-cyclodextrin: ground state binding and photochemistry

Marconi

Mezzina

Manet

et al. 2011

Photochem Photobiol Sci

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“…It is therefore interesting to note that the relative size of AHOMO and ALUMO is also correctly deduced without any calculations by inspection of the perimeter orbitals using the PMO method,5 in spite of its crude nature. Figure 5 shows the nodal properties of the frontier MO's of the [16]annulene dianion and indicates the interactions with the proper symmetry combinations of the MO's of four ethylene units. Their union, plus four aza replacements, generate the porphyrin dianion.…”

Section: Introductionmentioning

confidence: 99%

“…It is clear that its LUMO remains degenerate: even after the perturbation, the -a and -s orbitals are related by a 90°T Nodal properties of the HOMO and LUMO of the [16]annulene dianion, and the interactions due to the union with four ethylenes and four aza nitrogens: black circles, interactions which lower the orbital energy; white circles, interactions which raise the orbital energy. The effect of the perturbations on orbital energies in the process [16]annulene dianion -* porphyrin dianion is shown below. In the hydrogenated analogues 1-5, the interactions with one or more of the ethylene units are missing, with predictable effects on the relative size of AHOMO and ALUMO.…”

Section: Introductionmentioning

confidence: 99%

“…The best way to further improvement may be in adopting a CNDO or 1NDO type of approach, which, however, underestimates the extent of orbital and state pairing in alternant x systems and thus produces significant contributions even where essentially none should exist. 16 (iii) Neglects Inherent to the Perimeter Model. Some of the shortcomings of the present approach were already mentioned in part l.2 Perhaps the most drastic approximation made in the evaluation of B terms is the extremely small number of states considered.…”

Section: Introductionmentioning

confidence: 99%

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Magnetic circular dichroism of cyclic .pi.-electron systems. 2. Algebraic solution of the perimeter model for the B terms of systems with a (4N + 2)-electron [n]annulene perimeter

Michl¹

1978

J. Am. Chem. Soc.

162

133

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“…The electric transition moments m were calculated with the dipole velocity operator method and the magnetic moment m with the complete angular momentum operator method. 81…”

Section: Calculation Of Circular Dichroismmentioning

confidence: 99%

Combination of spectroscopic and computational methods to get an understanding of supramolecular chemistry of drugs: from simple host systems to biomolecules

Monti

Manet

Marconi

2011

Phys. Chem. Chem. Phys.

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Circular dichroism (CD) spectra of non-covalent ligand : biomolecule couples contain information on the equilibrium geometries of the associated structures that can be retrieved upon comparison of the sign and intensity of the experimental CD bands with the quantum mechanically calculated rotational strengths of low energy supramolecular complexes, obtained from molecular modelling methods. For both chiral and achiral ligands this approach proved useful to reach a structure based rationale of ground and excited state properties of the non-covalent ligand : protein associates. In this Perspective we illustrate the potential of this method focusing on the main achievements of our recent spectroscopic, conformational and photochemical studies on drug-albumin complexes and collocate it in the frame of current methodologies of molecular modelling and spectroscopic investigation of ligand : biomolecule binding.

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CNDO/S calculations of magnetic circular dichroism of polyacenes

Cited by 11 publications

References 21 publications

Stereoselective interaction of ketoprofen enantiomers with β-cyclodextrin: ground state binding and photochemistry

Stereoselective interaction of ketoprofen enantiomers with β-cyclodextrin: ground state binding and photochemistry

Magnetic circular dichroism of cyclic .pi.-electron systems. 2. Algebraic solution of the perimeter model for the B terms of systems with a (4N + 2)-electron [n]annulene perimeter

Combination of spectroscopic and computational methods to get an understanding of supramolecular chemistry of drugs: from simple host systems to biomolecules

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