Transition structure chameleonic

Hayase, S. Hrovat, D. A. Borden, W. T. A B3LYP study of the effects of phenyl substituents on 1,5-hydrogen shifts in 3-(Z)-l,3-pentadiene provides evidence against a chameleonic transition structure, J. Am. Chem. Soc. 2004,126,10028-10034. 

A collection of active protein sequences or protein fragments or subsequences, collected in the form of function-oriented databases, http //bioinformatica. isa.cnr.it/ACS/. AIRS —Autoimmune Related Sequences BAC—Bioactive Peptides CH AMSE—Chameleon Sequences (sequences that can adopt both an alpha helix and beta sheet conformation DORRS — Database of RGD-Related Sequences DVP — Delivery Vector Peptides SSP — Structure-Solved Peptides TRANSIT — Transglutamination Sites. 

The larger A cations, usually alkaline or rare earth elements, with inert d" or f electronic structure, act as structural stabilizers and do not offer much to the redox catalytic activity. The smaller B cations can be 3d, 4d, or 5d transition metal elements and are the main catalytic sites/centers in such solids due to their ability to undergo reversed redox cycles without destruction of the structure. In the vast majority of catalytic studies, 3d cations are employed due to obvious economic reasons. Nevertheless, almost 95% of the elements of the periodic table can participate in perovskites and these many possible combinations result in a plethora of diverse, and sometimes imexpected, properties of such solids, which have been nick-named chemical chameleons. 

D. Astruc - Transition Metal Radicals Chameleon Structure and Catalytic Functions, Acc. Chem. Res. 24,36,1991. 

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