Steric hindrance influence of a diazo link upon mesogenic properties of some ligands and related copper complexes

Abstract The ESR spectroscopy is used for the study of the motion of Cu(en)22+ and Cu(tmen)(OH)2 in fully hydrated X and Y zeolites. At room temperature steric hindrance in the faujasite cavities and slow motion condition lead to partially anisotropic spectra. In frozen samples, calculation of bonding coefficients indicate small interaction with surface walls.

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METABOLISM OF 17α-HYDROXYPROGESTERONE-4-14C-17α-CAPROATE BY HOMOGENATES OF RAT LIVER AND HUMAN PLACENTA

Acta Endocrinologica ◽

10.1530/acta.0.0360511 ◽

1961 ◽

Vol 36 (4) ◽

pp. 511-519 ◽

Cited By ~ 6

Author(s):

Margaret Wiener ◽

Charles I. Lupa ◽

E. Jürgen Plotz

Keyword(s):

Rat Liver ◽

Human Placenta ◽

Steric Hindrance ◽

Placental Tissue ◽

Caproic Acid ◽

Major Product ◽

Side Chain ◽

Anaerobic Conditions ◽

Prolonged Action ◽

Long Acting

ABSTRACT 17α-hydroxyprogesterone-4-14C-17α-caproate (HPC), a long-acting progestational agent, was incubated with homogenates of rat liver and human placenta. The rat liver was found to reduce Ring A of HPC under anaerobic conditions to form allopregnane-3β,17α-diol-20-one-17α-caproate and pregnane-3β,17α-diol-20-one-17α-caproate, the allopregnane isomer being the major product. The caproic acid ester was neither removed nor altered during the incubation. Placental tissue did not attack HPC under conditions where the 20-ketone of progesterone was reduced. It is postulated that this absence of attack on the side chain is due to steric hindrance from the caproate ester, and that this may account for the prolonged action of HPC.

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Tyrosine-Selective Bioconjugation with Iminoxyl Radicals

10.26434/chemrxiv.12278717 ◽

2020 ◽

Author(s):

Katsuya Maruyama ◽

Takashi Ishiyama ◽

Yohei Seki ◽

Kounosuke Oisaki ◽

Motomu Kanai

Keyword(s):

Reaction Time ◽

Steric Hindrance ◽

Room Temperature ◽

Water Soluble ◽

Light Irradiation ◽

Sodium Ascorbate ◽

Iminoxyl Radical ◽

Short Reaction Time ◽

Modified Peptides ◽

The Stability

A novel Tyr-selective protein bioconjugation using the water-soluble persistent iminoxyl radical is described. The conjugation proceeded with high Tyr-selectivity and short reaction time under biocompatible conditions (room temperature in buffered media under air). The stability of the conjugates was tunable depending on the steric hindrance of iminoxyl. The presence of sodium ascorbate and/or light irradiation promoted traceless deconjugation, restoring the native Tyr structure. The method is applied to the synthesis of a protein-dye conjugate and further derivatization to azobenzene-modified peptides.

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Synthesis of Conjugated Triynes via Alkyne Metathesis

10.26434/chemrxiv.8342534.v2 ◽

2019 ◽

Author(s):

Idriss Curbet ◽

Sophie Colombel-Rouen ◽

Romane Manguin ◽

Anthony Clermont ◽

Alexandre Quelhas ◽

...

Keyword(s):

Steric Hindrance ◽

High Selectivity ◽

Alkyne Metathesis ◽

Cross Metathesis ◽

Synthetic Strategy ◽

Sterically Hindered ◽

Site Selective

<div> <div> <div> <div> <p>The synthesis of conjugated triynes by molybdenum-catalyzed alkyne metathesis is reported. Strategic to the success of this approach is the utilization of sterically-hindered diynes that allowed for the site- selective alkyne metathesis to produce the desired con- jugated triyne products. The steric hindrance of alkyne moiety was found to be crucial in preventing the for- mation of diyne byproducts. This novel synthetic strategy was amenable to self- and cross-metathesis providing straightforward access to the corresponding symmetrical and dissymmetrical triynes with high selectivity. </p> </div> </div> </div> </div>

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Synthesis, characterization and biological activities of 1,3,4-oxadiazole derivatives of nalidixic acid and their copper complexes

10.31221/osf.io/g7mx8 ◽

2019 ◽

Author(s):

Chem Int

Keyword(s):

Nalidixic Acid ◽

Copper Complexes ◽

Biological Activities ◽

Bidentate Coordination ◽

Antibacterial And Antifungal Activities ◽

Elemental Analyses ◽

Oxadiazole Derivatives ◽

Antibacterial And Antifungal ◽

Derivatives Of ◽

Substituted 1

A series of novel 1, 3, 4-oxadiazole analogues was synthesized from cyclization of hydrazones of substituted 1-ethyl-1,4-dihydro-7-methyl-4-oxo-1,8-naphthyridine-3-carbohydrazides were prepared from nalidixic acid. The structures of synthesized oxadiazole derivatives and their copper complexes were elucidated on the basis of FTIR, elemental analyses, 1H-NMR and atomic absorption spectral analysis. It was observed from spectral data that metal ligand ratio was 1:1 in all copper complexes and they were bidentate, coordination was found to be done through oxygen of 4-oxo group and nitrogen of oxadiazole ring. The synthesized compounds were further evaluated with biological activities and compared with parent hydrazones. Copper complexes possess antibacterial and antifungal activities better than the oxadiazoles while they have better antioxidant activity then copper complexes. Parent hydrazones were better in all biological activities than synthesized oxadiazoles.

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Complexes of Cu (II) with a-Ketoglutaric Acid and 1- (o-tolyl) Biguanide Synthesis, characterization and biological Activity

Revista de Chimie ◽

10.37358/rc.19.10.7605 ◽

2019 ◽

Vol 70 (10) ◽

pp. 3603-3610

Author(s):

Madalina Mihalache ◽

Cornelia Guran ◽

Aurelia Meghea ◽

Vasile Bercu ◽

Ludmila Motelica ◽

...

Keyword(s):

Staphylococcus Aureus ◽

Pseudomonas Aeruginosa ◽

Antimicrobial Activity ◽

Antibacterial Activity ◽

Biological Activity ◽

Candida Albicans ◽

Antifungal Activity ◽

Copper Complexes ◽

Substrate Adhesion ◽

Inert Substrate

The three copper complexes having a-ketoglutaric acid (H2A) and 1- (o-tolyl) biguanide (TB) ligands have been synthesized and characterized. The proposed formulas for these complexes are: [Cu(TB)(HA)]Cl (C1), [Cu(TB)(HA)CH3COO]�H2O (C2) and [Cu(TB)(HA)](NO3) (C3) where HA represents deprotonated H2A. The complexes obtained were tested for antibacterial activity against Staphylococcus aureus ATCC 25923 and Pseudomonas aeruginosa ATCC 27853, antifungal activity on Candida albicans ATCC 10231 and antitumor activity on HeLa tumor cells. Due to the antitumor, antifungal, antimicrobial activity and inhibition of inert substrate adhesion, complexes synthesized could be used for potential therapeutic applications.

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Copper Complexes of Henna-Sulforaphane Conjugates as Potent Antiproliferative Agents Against Human Myeloma KBM-5 Cells Through Blockade of Transcription Factor NF-κB

Letters in Drug Design & Discovery ◽

10.2174/157018007784620059 ◽

2007 ◽

Vol 4 (4) ◽

pp. 257-262 ◽

Cited By ~ 1

Author(s):

K. Shirisha ◽

J. Patole ◽

S. Padhye ◽

E. Sinn ◽

S. Shishodia ◽

...

Keyword(s):

Transcription Factor ◽

Copper Complexes ◽

Antiproliferative Agents

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Regioselectivity of nucleophilic aromatic photosubstitution in the biphenyl series. Photohydrolysis of some dimethoxynitrobiphenyls

Collection of Czechoslovak Chemical Communications ◽

10.1135/cccc19872482 ◽

1987 ◽

Vol 52 (10) ◽

pp. 2482-2491 ◽

Cited By ~ 1

Author(s):

Ján Urban ◽

Petr Kuzmič ◽

David Šaman ◽

Milan Souček

Keyword(s):

Nitro Group ◽

Steric Hindrance ◽

The Other ◽

Quantum Yields ◽

Hydroxide Anion ◽

Tert Butanol ◽

Nitro Derivatives

Anaerobic photolysis of dimethoxynitrobiphenyls IIIa-VIa in aqueous alkaline tert-butanol gave products of nucleophilic photosubstitution of methoxyl by hydroxide anion, while the dimethoxybiphenyls Ia and IIa were found unreactive. Regioselectivity of the reaction was examined in view of a possible “extended meta activation” by the nitro group. The most reactive substrate IIIa gives both C-3 and C-4 substitution products with an unsubstantial preference for the latter, which opposes the “extended meta selectivity” rule. All of the other compounds obey the rule, and 3,4-dimethoxy-3'-nitrobiphenyl (IVa) even displayed absolute selectivity by yielding C-3 substituted compound as the only product. 2,5-Dimethoxy substituted compounds underwent photosubstitution which much lower quantum yields than their 3,4-substituted counterparts, most probably due to some steric hindrance of conjugation. Similarly, 3-nitro-substituted biphenyls exhibited much lower overall reactivity than 4-nitro derivatives.

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