Spectroscopic Studies of the Simpler Porphyrins III. The Absorption Spectra ofms‐Tetraphenylporphine and a Series of Its Metal Complex Salts

1941 ◽  
Vol 9 (7) ◽  
pp. 497-502 ◽  
Author(s):  
V. M. Albers ◽  
H. V. Knorr
Keyword(s):  
Metal Complex ◽  
Absorption Spectra ◽  
Spectroscopic Studies ◽  
Complex Salts

Cobaloxime-Based Double Complex Salts as Efficient and Versatile Catalysts for the Light-Driven Hydrogen Evolution Reaction

2020 ◽  
Author(s):  
Elisabeth Hofmeister ◽  
Jisoo Woo ◽  
Tobias Ullrich ◽  
Lydia Petermann ◽  
Kevin Hanus ◽  
...  
Keyword(s):  
Hydrogen Evolution ◽  
Hydrogen Evolution Reaction ◽  
Systematic Study ◽  
Cobalt Complexes ◽  
Spectroscopic Studies ◽  
Double Complex ◽  
Double Complex Salts ◽  
Noble Metal Catalysts ◽  
Reduction Potentials ◽  
Complex Salts

Cobaloximes and their BF<sub>2</sub>-bridged analogues have emerged as promising non-noble metal catalysts for the photocatalytic hydrogen evolution reaction (HER). Herein we report the serendipitous discovery that double complex salts such as [Co(dmgh)<sub>2</sub>py<sub>2</sub>]<sup>+</sup>[Co(dmgBPh<sub>2</sub>)<sub>2</sub>Cl<sub>2</sub>]<sup>-</sup> can be obtained in good yields by treatment of commercially available [Co(dmgh)<sub>2</sub>pyCl] with triarylboranes. A systematic study on the use of such double complex salts and their single salts with simple counterions as photocatalysts revealed HER activities comparable or superior to existing cobaloxime catalysts and suggests ample opportunities for this compound class in catalyst/photosensitizer dyads and immobilized architectures. Preliminary electrochemical and spectroscopic studies indicate that one key advantage of these charged cobalt complexes is that the reduction potentials as well as the electrostatic interaction with charged photosensitizers can be tuned.

SPECTROSCOPIC STUDIES OF KETO–ENOL EQUILIBRIA: PART 2. ANOMALOUS ULTRAVIOLET ABSORPTION SPECTRA OF SATURATED 1,2-DICYANO ESTERS

1962 ◽  
Vol 40 (12) ◽  
pp. 2272-2277 ◽  
Author(s):  
T. R. Kasturi ◽  
B. N. Mylari ◽  
A. Balasubramanian ◽  
C. N. R. Rao
Keyword(s):  
Absorption Band ◽  
Absorption Spectra ◽  
Spectroscopic Studies ◽  
Anomalous Behavior ◽  
Enol Form ◽  
Ultraviolet Absorption ◽  
Polar Solvents ◽  
Solvent Dependence

1,2-Dicyano esters show an absorption band around 245 mμ in alcoholic solutions which is not found in non-polar and other polar solvents. This anomalous behavior has been found to be due to the unusual solvent dependence of the equilibrium between the keto and enol forms. The intensity of the absorption band in alcoholic solutions decreases with increase in concentration of the 1,2-dicyano ester, indicating association of the enol form. The keto–enol equilibrium is also found to be sensitive to the substituent R of the alcohol ROH.

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