Merging Constitutional and Motional Covalent Dynamics in Reversible Imine Formation and Exchange Processes
摘要:
The formation and exchange processes of imines of benzaldehyde have been studied, showing that the former has features of for dynamic covalent chemistry, displaying high efficiency and fast rates. The monoimines formed with aliphatic a,alpha,omega-diamines display an internal exchange process of self-transimination type, inducing a local motion of either "stepping-in-place" or "single-step" type by bond interchange, whose rate decreases rapidly with the distance of the terminal amino groups. Control of the speed of the process over a wide range may be achieved by substituents, solvent composition, and temperature. These monoimines also undergo intermolecular exchange, thus merging motional and constitutional covalent behavior within the same molecule. With polyamines, the monoimines formed execute internal motions that have been characterized by extensive one-dimensional, two-dimensional, and EXSY proton NMR studies. In particular, with linear polyamines, nondirectional displacement occurs by shifting of the aldehyde residue along the polyamine chain serving as molecular track. lmines thus behave as simple prototypes of systems displaying relative motions of molecular moieties, a subject of high current interest in the investigation of synthetic and biological molecular motors. The motional processes described are of dynamic covalent nature and take place without change in molecular constitution. They thus represent a category of dynamic covalent motions, resulting from reversible covalent bond formation and dissociation. They extend dynamic covalent chemistry into the area of molecular motions. A major further step will be to achieve control of directionality. The results reported here for imines open wide perspectives, together with other chemical groups, for the implementation of such features in multifunctional molecules toward the design of molecular devices presenting a complex combination of motional and constitutional dynamic behaviors.
Competition-driven selection in covalent dynamic networks and implementation in organic reactional selectivity
作者:P. Kovaříček、A. C. Meister、K. Flídrová、R. Cabot、K. Kovaříčková、J.-M. Lehn
DOI:10.1039/c5sc04924e
日期:——
Competition among reagents in dynamiccombinatoriallibraries of increased complexity leads to reactional self-sorting. This fundamental principle allowed development of selective dynamic protecting groups for controlled sequential derivatization of polyamines.
Synthesis, characterization and anticancer properties of (salicylaldiminato)platinum(II) complexes
作者:Alyssa E. Patterson、Jessica J. Miller、Brittany A. Miles、Erin L. Stewart、Josée-Marie E.J. Melanson、Christopher M. Vogels、Amanda M. Cockshutt、Andreas Decken、Pier Morin、Stephen A. Westcott
DOI:10.1016/j.ica.2014.02.028
日期:2014.5
Twelve new (salicylaldiminato) platinum(II) complexes have been prepared, characterized and examined for their in vitro cytotoxic properties against three human glioma cell lines LN18, LN405 and Hs683. Initial biotesting was done on platinum complexes 1-6, which display a wide range of physicochemical properties. Whereas introduction of aromatic rings in the complexes did not seem to have a significant impact on bioactivities, the length of the aliphatic group positively correlated with cytotoxicity in all cell lines. Complexes 2 and 3 were found to be particularly potent against LN18 cells as demonstrated by stronger cell growth inhibition when compared to cisplatin. These initial findings led us to develop an additional series of mono (salicylaldiminato) platinum(II) complexes 7-12, which were subjected to additional cytotoxicity studies but were less cytotoxic compared to the bis Schiff base complexes. These organometallic compounds could serve as interesting starting points for the development of novel therapeutic strategies to treat brain tumors. (C) 2014 Elsevier B.V. All rights reserved.
Synthesis, crystallographic, and theoretical investigation of <i>fac</i>-[Re<sup>I</sup>(salen)(CO)<sub>3</sub>(S)] complexes, salen = monocharged bidentate Schiff-base and S = pyridine, CH<sub>3</sub>OH
作者:Alice Brink、Hendrik G. Visser、Andreas Roodt
DOI:10.1080/00958972.2010.538050
日期:2011.1.10
Two rhenium(I) complexes of the form fac-[Re(L-L')(CO)3(S)] were synthesized (L-L' = N-O salen-type bidentate ligand, S = coordinating methanol or pyridine) and the crystal structures of fac-[tricarbonylmethanol-(2-(3-methylbutyliminomethyl)phenolato)rhenium(I)] and fac-[tricarbonyl-(2-(3-methylbutyliminomethyl)phenolato)pyridinerhenium(I)] are reported. The influence of the coordinating neutral monodentate ligand in these fac-[tricarbonyl(N,O-salen)rhenium(I)] complexes was investigated both in solid state and at theoretical level using X-ray diffraction, IR, NMR, and DFT calculations.