Preparation and Properties of Oxo-Centered Trinuclear Chromium(III) Complexes with Bridging Optically Active Amino Acids, [Cr3(μ3-O)(μ-O,O′-amino-acid)6(H2O)3]7+

1991 ◽  
Vol 64 (11) ◽  
pp. 3463-3465 ◽  
Author(s):  
Hisashi Kato ◽  
Kou Nakata ◽  
Akira Nagasawa ◽  
Tadashi Yamaguchi ◽  
Yoichi Sasaki ◽  
...  
Keyword(s):  
Amino Acids ◽  
Amino Acid ◽  
Optically Active

Circular dichroism spectra of amino acid complexes. II. Chelated amino acid complexes with the CoN5O chromophore

1970 ◽  
Vol 23 (9) ◽  
pp. 1735 ◽  
Author(s):  
CJ Hawkins ◽  
PJ Lawson
Keyword(s):  
Amino Acids ◽  
Circular Dichroism ◽  
Amino Acid ◽  
Visible Region ◽  
Optically Active ◽  
Circular Dichroism Spectra ◽  
Amino Acid Complexes ◽  
Similar Series ◽  
Cotton Effects ◽  
Circular Dichroïsm

The circular dichroism spectra of a series of optically active (α-aminocarboxylato)tetraamminecobalt(111) complexes have been measured in aqueous solution, and in the presence of salts of polarizable anions. The observed spectra in the visible region have been analysed to determine the signs of the Cotton effects of the three components of the 1A1g ↔ 1T1g cobalt(111) transition. For L-amino acids, the transition with A2g(D4h) parentage is negative, and the two transitions with Eg(D4h) parentage have opposite signs. Published circular dichroism spectra of complexes of the type [Co(en)2(L-am)]2+ were similarly interpreted in terms of a perturbed tetragonal chromophore, and it was shown that the vicinal effect of the L-amino acids imposed the same signs onto the component transitions as for the tetraammines and for a similar series of pentaamminecobalt(111) complexes.

scholarly journals On-off transition and ultrafast decay of amino acid luminescence driven by modulation of supramolecular packing

2021 ◽  
Author(s):  
Zohar A. Arnon ◽  
Topaz Kreiser ◽  
Boris Yakimov ◽  
Noam Brown ◽  
Ruth Aizen ◽  
...  
Keyword(s):  
Amino Acids ◽  
Amino Acid ◽  
Crystal Packing ◽  
Optical Transition ◽  
Optically Active ◽  
Chemical Characteristics ◽  
Electronic Interactions ◽  
Visible Luminescence ◽  
Lifetime Decay

AbstractIt has been experimentally observed that various biomolecules exhibit clear luminescence in the visible upon aggregation, contrary their monomeric state. However, the physical basis for this phenomenon is still elusive. Here, we systematically examine all coded amino acids to provide non-biased insights into this phenomenon. Several amino acids, including non-aromatic, show intense visible luminescence. While lysine crystals display the highest signal, the very chemically similar non-coded ornithine does not, implying a role for molecular packing rather than the chemical characteristics of the molecule. Furthermore, cysteine show luminescence that is indeed crystal-packing-dependent as repeated rearrangements between two crystal structures result in a reversible on-off optical transition. In addition, ultrafast lifetime decay is experimentally validated, corroborating a recently raised hypothesis regarding the governing role of nπ* states in the emission formation. Collectively, our study supports the hypothesis that electronic interactions between molecules that are non-fluorescent and non-absorbing at the monomeric state may result in reversible optically-active states by the formation of supramolecular fluorophores.

Spectroscopic studies on some sulphur-containing amino acid complexes of cobalt, nickel and copper

1974 ◽  
Vol 27 (8) ◽  
pp. 1629 ◽  
Author(s):  
RJ Magee ◽  
W Mazurek ◽  
MJ O'Conner ◽  
AT Phillip
Keyword(s):  
Amino Acids ◽  
Amino Acid ◽  
Structural Analysis ◽  
Energy Level ◽  
Spectroscopic Studies ◽  
Optically Active ◽  
Ligand Field ◽  
Spectral Measurements ◽  
X Ray ◽  
Cobalt Nickel

The synthesis of three potentially sexadentate optically active sulphur-containing amino acids, 2,9- diamino-4,7-dithiadecanedioic acid [(R,R)-ebc], 2,ll-diamino-5,8-dithiadodecanedioic acid [(S,S)- ebhc] and 2,7-di(3'-thiabuty1)-3,6-diazaoctanedioic acid [(S,S)-ebm] are described. Some metal complexes of the acids with cobalt, nickel and copper are characterized by spectroscopic measurements. The complex�� (-)589[Co{(S,S)-ebm}] ClO4 is formed stereospecifically and an X-ray structural analysis shows it to have the Δ-trans(O) configuration. The c.d. spectrum shows the presence of three bands due to the splitting of the T1g energy level by the effective C2 symmetry of the ligand field. Some polymeric cobalt(11) and nickel(11) complexes are also described. Spectral measurements indicate an octahedral coordination of the ligands involved. Several copper(11) complexes are also described.

Enantioselective synthesis of β-amino acid derivatives via nickel-promoted regioselective carboxylation of ynamides and rhodium-catalyzed asymmetric hydrogenation

2016 ◽  
Vol 14 (42) ◽  
pp. 10080-10089 ◽  
Author(s):  
Nozomi Saito ◽  
Iman Abdullah ◽  
Kayoko Hayashi ◽  
Katsuyuki Hamada ◽  
Momoko Koyama ◽  
...  
Keyword(s):  
Amino Acids ◽  
Amino Acid ◽  
Active Form ◽  
Asymmetric Hydrogenation ◽  
Optically Active ◽  
Enantioselective Synthesis ◽  
Amino Acid Derivatives

Nickel-promoted carboxylation of ynamides followed by rhodium-catalyzed asymmetric hydrogenation provided α-substituted-β-amino acids in an optically active form.

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