Copper(II) complexes with reduced Schiff base ligands of amino acids possessing nonpolar side chains with salicylaldehyde have been synthesized. Ternary complexes with imidazole, 1,10-phenanthroline, and pyridine have been prepared and characterized for N-(2-hydroxybenzyl)-D,L-alanine. The crystal structures of [(N-(2-hydroxybenzyl)-D,L-alanine)(1,10-phenanthroline)Cu(II)] monohydrate ([Cu(SAla)phen].H(2)O) and [(N-(2-hydroxybenzyl)-D,L-alanine)(imidazole)Cu(II)] ([Cu(SAla)Him]), have been determined. [Cu(SAla)phen].H(2)O crystallized in space group P&onemacr;, with a = 8.718(2) Å, b = 10.886(3) Å, c = 11.693(2) Å, alpha = 71.32(2) degrees, beta = 85.27(2) degrees, gamma = 70.21(2) degrees, and Z = 2. The copper atom is five coordinate, with SAla acting as a tridentate ONO chelator through the carboxylato and phenolato oxygens and the amine nitrogen. The remaining donors are provided by the phen nitrogens. [Cu(SAla)Him] crystallized in space group P2(1)/n, with a = 10.353(1) Å, b = 6.714(1) Å, c = 18.769(2) Å, beta = 91.71(1) degrees, and Z = 4. The copper atom is four coordinate, with SAla acting as a tridentate ONO chelator with the neutral imidazole moiety coordinated through nitrogen. In both complexes the ligand has two chiral centers due to the coordination of the N. Molecular mechanics calculations show that unfavorable steric interactions would occur in the nonobserved R,R and S,S diastereomers. Compounds prepared have been characterized by a range of physicochemical techniques. The complexes may serve as stable models for the intermediates in enzymatic amino acid transformations.
A luminescent molecular rectangle [Au(4)(micro-PAnP)(2)(micro-bipy)(2)](OTf)(4) (1.(OTf)(4)) (PAnP = 9,10-bis(diphenylphosphino)anthracene, bipy = 4,4'-bipyridine, X = NO(3)(-) or OTf(-)), synthesized from the self-assembly of the molecular "clip" Au(2)(micro-PAnP)(OTf)(2) and bipy, shows a large rectangular cavity of 7.921(3) x 16.76(3) A. The electronic absorption and emission spectroscopy, and electrochemistry of the metallacyclophane, have been studied. The 1(4+) ions are self-assembled into 2D mosaic in the solid state via complementary edge-to-face interactions between the Ph groups. (1)H NMR titrations ratify the 1:1 complexation between 1(4+) and various aromatic molecules. Comparing the structures of the inclusion complexes indicates an induced-fit mechanism operating in the binding. The emission of 1(4+) is quenched upon the guest binding. The binding constants are determined by both (1)H NMR and fluorescence titrations. Solvophobic and ion-dipole effects are shown to be important in stabilizing the inclusion complexes.
Construction by shining light! A [2+2] cycloaddition reaction in a 2D coordination polymer accompanied by single‐crystal‐to‐single‐crystal structural transformation to a 3D structure highlights the retrosynthesis of a 3D structure from a 2D layer compound (see scheme, Zn red, 4‐styrylpyridine blue/turquoise).
A pair of bpe-H(+) ligands in a zwitter-ionic complex undergoes photochemical cycloaddition quantitatively accompanied by proton transfer and the cyclobutane ring isomerizes slowly in solution to two more isomers, catalyzed by CF(3)CO(2)H acid.
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.