Theoretical study of spectroscopic properties of insulated molecular wires formed by substituted oligothiophenes and cross‐linked α‐cyclodextrin

Abstract

The inclusion compound formed between cross‐linked α‐cyclodextrin dimer and substituted oligothiophene, was investigated using density functional theory (DFT). Energy gap, spectroscopy (IR, UV–vis, 13C NMR, and 1H NMR) and first hyperpolarizability data were analyzed for the free species and inclusion compound, pp‐PT@(αCD–αCD). The semiconducting property of the included pp‐PT was not substantially affected on inclusion, with the energy gap increasing by only 10% after interaction with αCD–αCD. On the other hand, the nonlinear optical (NLO) response was significantly decreased, with the first hyperpolarizability, β, predicted to be just more than 60% lower for the [2]rotaxane than for free pp‐PT, but still having considerable magnitude. This was explained by the two‐state model based on the charge‐transfer contribution to the electronic transitions. The sensitivity of electronic spectra might also be useful for the inclusion complex characterization. The IR spectrum was slightly sensitive to the host–guest interaction and the calculated 13C NMR and 1H NMR chemical shifts for the pp‐PT guest showed appreciable variations of 5–10 and 1–1.5 ppm, respectively, and so can be used for the characterization of inclusion compounds. We concluded that the formation of inclusion complexes with CDs, seems indeed very promising and the use of encapsulating conducting material should be experimentally pursued. © 2011 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys, 2011

Theoretical and Experimental Study of Inclusion Complexes Formed by Isoniazid and Modified β-Cyclodextrins: 1H NMR Structural Determination and Antibacterial Activity Evaluation

“…In this sense, recent PCM chemical shift theoretical results reported for quebrachitol , and also calix[ n ]arenes inclusion complexes provide support to the approach used in this work, consisting of DFT single-point NMR calculations using the PCM model with molecular geometries optimized in the vacuum. Changes in NMR chemical shift values for guest and host molecules due to complex formation can be used as strong evidence of the formation of inclusion complexes, as is exemplified in the case of the study of molecular wires formed from polythiophenes and cyclodextrins …”

“…Changes in NMR chemical shift values for guest and host molecules due to complex formation can be used as strong evidence of the formation of inclusion complexes, as is exemplified in the case of the study of molecular wires formed from polythiophenes and cyclodextrins. 55 Theoretical and experimental 1 H NMR spectra for free isoniazid and Me-βCD are shown in Figure 9, with the specification of the hydrogen atom labels for the analysis of 1 H NMR spectra given in Figure 1. Presuming a full inclusion of the guest molecule, only the inner hydrogen atoms (H3 and H5) of cyclodextrin are relevant for the analysis of chemical shift variations due to complex formation.…”

Revealing the Binding Process of New 3-Alkylpyridine Marine Alkaloid Analogue Antimalarials and the Heme Group: An Experimental and Theoretical Investigation

“…In addition, the use of a better description of the atoms participating in the relevant linkages was assessed, adding a double-ζ quality basis set and polarization functions for the O, N, and Fe atoms. This mixed basis set approach has been successfully used in previous work. − …”

Cyclodextrin-based rotaxanes

“…A valuable property of CDs in the facile functionalization of their wide and narrow rims. The chemistry and applications of CDs are a topic of an enormous number of works [1][2][3][4][5][6][7][8][9][10].…”