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1.
The influence of electrolytes on the photoredox kinetics and cage escape yields of redox products (πredox) in the quenching of Ru(bpy)2+*3 by methylviologen (MV2+), TlIII and HgII have been investigated. For all three quenchers πredox appears to be strongly dependent on the nature of the anion. Photoelectrochemical cells based on the latter systems are described. 相似文献
2.
Kuppuswamy Kalyanasundaram Enrico Borgarello Michael Grutzel 《Helvetica chimica acta》1981,64(1):362-366
Illumination of aqueous CdS dispersions loaded with Pt and RuO2 by visible light produces hydrogen and oxygen in stoichiometric proportion. No degradation of the photocatalyst is noted after 60 h of irradiation time. The RuO2 deposit on the particle surface greatly accelerates the transfer of holes from the semiconductor valence band to the aqueous solution thus inhibiting photocorrosion. 相似文献
3.
4.
Ulrich Vgeli Wolfgang von Philipsborn Kuppuswamy Nagarajan Mohan D. Nair 《Helvetica chimica acta》1978,61(2):607-617
Heterocyclic compounds obtained by addition of acetylenedicarboxylic acid esters to thioureas, cyclic amidines and o-difunctionalized aromatic systems have been studied by 13C-NMR. In particular, C, H-spin-coupling constants over two and three bonds were used to differentiate between the various constitutional isomers and to establish the configuration of trisubstituted exocyclic C, C-double bonds. The configurational significance and diagnostic value of vicinal cis and trans C,H-spin coupling is again demonstrated in the present series. 相似文献
5.
Srinivasachari Rajappa Kuppuswamy Nagarajan Kailasam Venkatesan Nirupa Kamath Vipanjeri Madabhusi Padmanabhan Wolfgang von Philipsborn Ban Chin Chen Raffaelo Müller 《Helvetica chimica acta》1984,67(7):1669-1680
The 1H-NMR spectra of 2-(nitromethylidene)pyrrolidine ( 7 ), 1-methyl-2-(nitromethylidene)imidazolidind ( 10 ) and 3-(nitromethylidene)tetrahydrothiazine ( 11 ) in CDCl3 and (CD3)2SO indicate that these compounds have the intramolecularly H-bonded structures (Z)- 7 , (E)- 10 and (Z)- 11 while the N-methyl derivative 8 of 7 is (E)-configurated in both solvents. 1-Benzylamino-1-(methyltio)-2-nitroehtylene ( 13 ), an acylic model, has the H-bonded configuration (E)- 13 in CDCl3 and in (CD3)2SO. 2-(Nitromethylidene)thiazolidine ( 3 ) has the (E)-configuration in CDCl3 but exists in (CD3)2SO as a mixture of (Z)- and (E)-isomers with the former predominating. Both species are detected to varying proportions in a mixture of the two solvents. 15N-NMR spectroscopy of 3 ruled out unambiguously the nitronic acid structure 6 and the nitromethyleimine structure 5 . The N-methyl derivative 4 of 3 is (Z)-configurated in (CD3)2SO. Comparison of the olefinic proton shifts of (Z)- 3 and (Z)- 4 with those of analogues and also of 1,1-bis(methylti)-2-nitroethylene ( 12 ) shows decreased conjugation of the lone pair of electrons of the ring N-atom in (Z)- 3 and (Z)- 4 . This is also supported by 13C-NMR studies. Plausible explanations for the phenomenon are offered by postulating that the ring N-atoms are pyramidal in (Z)- 3 and (Z)- 4 and planar in other cases or, alternatively, that the conjugated nitroenamine system gets twisted due to steric interaction between the NO2-group and the ring S-atom. Single-crystal X-ray studies of 3 and 8 show that the former exists in the (Z)-configuration and the latter in (E)-configuration; the ring N-atom in the former has slightly more pyramidal character than in the latter. 相似文献
6.
7.
Dr. Kuppuswamy Arumugam C. Daniel Varnado Jr. Dr. Stephen Sproules Dr. Vincent M. Lynch Prof. Dr. Christopher W. Bielawski 《Chemistry (Weinheim an der Bergstrasse, Germany)》2013,19(33):10866-10875
High yielding syntheses of 1‐(ferrocenylmethyl)‐3‐mesitylimidazolium iodide ( 1 ) and 1‐(ferrocenylmethyl)‐3‐mesitylimidazol‐2‐ylidene ( 2 ) were developed. Complexation of 2 to [{Ir(cod)Cl}2] (cod=cis,cis‐1,5‐cyclooctadiene) or [Ru(PCy3)Cl2(?CH‐o‐O‐iPrC6H4)] (Cy=cyclohexyl) afforded 3 ([Ir( 2 )(cod)Cl]) and 5 ([Ru( 2 )Cl2(?CH‐o‐O‐iPrC6H4)]), respectively. Complex 4 ([Ir( 2 )(CO)2Cl]) was obtained by bubbling carbon monoxide through a solution of 3 in CH2Cl2. Spectroelectrochemical IR analysis of 4 revealed that the oxidation of the ferrocene moiety in 2 significantly reduced the electron‐donating ability of the N‐heterocyclic carbene ligand (ΔTEP=9 cm?1; TEP=Tolman electronic parameter). The oxidation of 5 with [Fe(η5‐C5H4COMe)Cp][BF4] as well as the subsequent reduction of the corresponding product [ 5 ][BF4] with decamethylferrocene (Fc*) each proceeded in greater than 95 % yield. Mössbauer, UV/Vis and EPR spectroscopy analysis confirmed that [ 5 ][BF4] contained a ferrocenium species, indicating that the iron center was selectively oxidized over the ruthenium center. Complexes 5 and [ 5 ][BF4] were found to catalyze the ring‐closing metathesis (RCM) of diethyl diallylmalonate with observed pseudo‐first‐order rate constants (kobs) of 3.1×10?4 and 1.2×10?5 s?1, respectively. By adding suitable oxidants or reductants over the course of a RCM reaction, complex 5 was switched between different states of catalytic activity. A second‐generation N‐heterocyclic carbene that featured a 1′,2′,3′,4′,5′‐ pentamethylferrocenyl moiety ( 10 ) was also prepared and metal complexes containing this ligand were found to undergo iron‐centered oxidations at lower potentials than analogous complexes supported by 2 (0.30–0.36 V vs. 0.56–0.62 V, respectively). Redox switching experiments using [Ru( 10 )Cl2(?CH‐o‐O‐iPrC6H4)] revealed that greater than 94 % of the initial catalytic activity was restored after an oxidation–reduction cycle. 相似文献
8.
We provide experimental evidence for stretching and collapse of neutral polymer layers, already adsorbed at an oil-in-water interface, due to its interaction with surfactants. Upon stretching, the first interaction length (2L(0)) follows a power law dependence on surfactant concentration ( proportional, variant C(x)(s), where x approximately 0.5 for cationic surfactants) and collapses in the presence of salt, as a relatively weak power law (C(-y)(s), where y=0.17), in good agreement with brush length decay for polyelectrolyte brushes. 相似文献
9.
The ketol and its acetate when refluxed in methanolic potassium hydroxide (5%) were found to rearrange to 4-methyl-8-acetyl-5,6,7,8-tetrahydro-1-naphthol . The epimeric acetate also behaved likewise. A mechanism is suggested for the rearrangement. 相似文献
10.