Аннотация:Molecular machines mentioned below are meant to be such molecular systems that use for functioning conformational mobility (i.e. hindered rotation around chemical bonds and with molecular construction deformations with formation and breakage of nonvalent bonds). Components of molecular machines move mainly by means of restricted diffusion. As an example of molecular machines of nonbiological nature catenanes (compounds with two interlocked molecular rings) could be proposed. Thus, for example, model catenane ((2)-(cyclo-bis(paraquat-p-phenylene))-(1(2,6)-tetrathiafulvalena-16(1,5)naphtalena-3,6,9,12,15,17,20,23,26, 29-decaoxatriacontaphane)-catenane) changes its redox status when electric field is applied, and rotation of the rings takes place. It occurs with fixation at certain moments of the influence. To find out characteristic properties of rings movements under various external conditions computer simulation of the molecule dynamics was carried out. Three cationic forms of the catenane were subjected to geometrical optimization and quantum chemical calculation using software package GAMESS. Molecular dynamics calculation was carried out with use of MoDyP package.
The results allowed to find out two types of movements - large-scale rotation of one of the constituent rings with times of about 30 ns at 2000 K and stochastic rotary movements of the rings with times less then a nanosecond. The latter times are of larger order than the system dielectric relaxation time. The leading role in coordination of mutual rotation is attributed to strongly charged cyclophane ring in which no rotation with angle more than 180 deg occurs. Distribution of charges in rings exerts strong influence upon dynamics of the catenane. The obtained results accord with known experimental data.
