Formamide conformational analysis

Volumen and Hydratationswarme der lonen. Zeitschrift filr Physik 1 45-48. aan C M and K B Wiberg 1990. Determining Atom-Centred Monopoles from Molecular Electro-itic Potentials. The Need for High Sampling Density in Formamide Conformational Analysis. imal of Computational Chemistry 11 361-373. 

CM Breneman, KB Wiberg. Determining atom-centered monopoles from molecular electrostatic potentials. The need for high sampling density m formamide conformational analysis. J Comput Chem 11 361-373, 1990. 

Centered Monopoles from Molecular Electrostatic Potentials. The Need for High Sampling Density in Formamide Conformational Analysis. 

C. M. Breneman and K, B. Wiberg,/. Comput. Chem., 11,361 (1990), Determining Atom-Centered Monopoles from Molecular Electrostatic Potentials. The Need lor High Sampling Density in Formamide Conformational Analysis. 

Breneman CM, Wibeig KB (1990) Determining atom-centered monopoles from molecular electrostatic potentials. The need for high sampling density in formamide conformational analysis. J Comput Chem ll(3) 361-373. doi 10.1002/jcc.540110311 Stephan DW (2015) Frustrated Lewis pairs from concept to catdysis. Acc Chem Res 48(2) 306-316. doi 10.1021/ar500375j Uzarewicz A (1964) Rocz Chem 38 599... 

A similar conformational analysis has been done with formamide derivatives, with secondary amides, and for hydroxamide acids. It is known that thioformamide has a larger rotational barrier than formamide, which can be explained by a traditional picture of amide resonance that is more appropriate for the thioformamide than formamide itself. Torsional barriers in a-keto amides have been reported, and the C—N bond of acetamides, thioa-mides, enamides carbamates (R2N—C02R), and enolate anions derived... 

Other modifications include a formamide residue (191), a ring fragmentation product of thymine, which exists as either a cis or a trans conformer. Both isomers are rotated out of the helix, and the bases on either side of (191) occupy the space vacated by it. A pyrene abasic site base pair in DNA duplexes adopts the usual B-form duplex, with the pyrene residue within the duplex stacking on adjacent nucleobases. The abasic site folds back over the opposite strand to shelter the hydrophobic base from exposure to water.The photoresponsive azobenzene analogues (133, R- and 5-forms) have been incorporated into DNA for NMR analysis. Both isomers intercalate between neighbouring base pairs, and the 5-isomer exhibits more disturbance in its duplex structure which is refiected in lower Tms compared to the R-isomer. ... 

Less ambiguous conclusions can be reached if the polarographic characteristics obtained under conditions which exclude adsorption and the effect of protolytic equilibria are compared. We therefore carried out such an analysis for the half-wave potential of the first wave formed by these compounds in the polarography of dimethyl-formamide solutions. In fact, under these conditions, we were able to observe the transmission of the substituent effect in the first series, which in accordance with the views expressed earlier indicated decrease of conjugation (p = +0.1). The polarographic data can thus be explained if a nonplanar conformation of the hydrazone molecules is adopted. 

---