Your browser doesn't support javascript.
loading
Mostrar: 20 | 50 | 100
Resultados 1 - 10 de 10
Filtrar
Mais filtros










Base de dados
Intervalo de ano de publicação
1.
Inorg Chem ; 62(20): 7779-7794, 2023 May 22.
Artigo em Inglês | MEDLINE | ID: mdl-37163348

RESUMO

This article dealt with the ruthenium and osmium derivatives of isomeric 1H-indazole-3-carboxylic acid/2H-indazole-3-carboxylic acid (H2L1) and 1H-benzimidazole-2-carboxylic acid (H2L2) along with the π-acidic bpy (bpy = 2,2'-bipyridine) and pap (pap = 2-phenylazopyridine) co-ligands. It thus extended structurally authenticated monomeric ([(bpy)2RuII(HL1-)]ClO4 [1]ClO4, (pap)2RuII(L12-) 2, (bpy)2OsII(L12-) 3, (pap)2OsII(L12-) 4, (bpy)2RuII(L22-) 5, (bpy)2OsII(L22-) 8, and (pap)2OsII(L22-) 9) and dimeric ([(bpy)2RuII(µ-L22-)RuII(bpy)2](ClO4)2 [6](ClO4)2) complexes. It also described modified L2'2- (L2'2- = 2,2'-bisbenzimidazolate)-bridged [(pap)2RuII(µ-L2'2-)RuII(pap)2](ClO4)2 [7](ClO4)2, where L2'2- was developed selectively with the {Ru(pap)2} metal fragment via in situ intermolecular C-C coupling of the two units of decarboxylated benzimidazolate. Moreover, chemical oxidation (OsII to OsIII) of (bpy)2OsII(L12-) 3 (E0 = 0.11 V versus SCE) and (bpy)2OsII(L22-) 8 (E0 = 0.12 V versus SCE) by AgClO4 yielded unprecedented OsIII-AgI derived polymeric {[(bpy)2OsIII-L12--AgI(CH3CN)](ClO4)2}n {[10](ClO4)2}n and dimeric [(bpy)2OsIII-L22--AgI(CH3CN)](ClO4)2 [11](ClO4)2 complexes as a function of trans and cis orientations of the active N2 donor with special reference to the carboxylate O2 of L2-, respectively. Microscopic (FE-SEM, TEM-EDX, and AFM) and DLS experiments suggested a homogeneously dispersed hollow spherical shaped morphology of {[10](ClO4)2}n with an average particle size of 200-400 nm as well as its non-dissociative feature in the aprotic medium. Experimental (structure, spectroscopy, and electrochemistry) and theoretical (DFT/TD-DFT) explorations revealed a redox non-innocent feature of L2- in the present coordination situations and the selective anion sensing (X = F-, CN-, and OAc-) event of [1]ClO4 involving a free NH group at the backface of HL1-, which proceeded via the NH···X hydrogen bonding interaction.

2.
Inorg Chem ; 61(40): 16122-16140, 2022 Oct 10.
Artigo em Inglês | MEDLINE | ID: mdl-36149433

RESUMO

The article deals with the newer classes of mononuclear: [(acac)2RuIII(H-Iz)(Iz-)] 1, [(acac)2RuIII(H-Iz)2]ClO4 [1]ClO4/[1']ClO4, and [(bpy)2RuII(H-Iz)(Iz-)]ClO4 [2]ClO4, mixed-valent unsymmetric dinuclear: [(acac)2RuIII(µ-Iz-)2RuII(bpy)2]ClO4 [3]ClO4, and heterotrinuclear: [(acac)2RuIII(µ-Iz-)2MII(µ-Iz-)2RuIII(acac)2] (M = Co:4a, Ni:4b, Cu:4c, and Zn:4d) complexes (H-Iz = indazole, Iz- = indazolate, acac = acetylacetonate, and bpy = 2,2'-bipyridine). Structural characterization of all the aforestated complexes established their molecular identities including varying binding modes (Na and Nb donors and 1H-indazole versus 2H-indazole) of the heterocyclic H-Iz/Iz- in the complexes. Unlike [1']ClO4 containing two NH protons at the backface of H-Iz units, the corresponding [1]ClO4 was found to be unstable due to the deprotonation of its positively charged quaternary nitrogen center, and this resulted in the eventual formation of the parent complex 1. A combination of experimental and density functional theory calculations indicated the redox noninnocent feature of Iz- in the complexes along the redox chain. The absence of intervalence charge transfer transition in the near-infrared region of the (Iz-)2-bridged unsymmetric mixed-valent RuIIIRuII state in [3]ClO4 suggested negligible intramolecular electronic coupling corresponding to a class I setup (Robin and Day classification). Heterotrinuclear complexes (4a-4d) exhibited varying spin configurations due to spin-spin interactions between the terminal Ru(III) ions and the central M(II) ion. Though both [3]ClO4 and 4a-4d displayed ligand (Iz-/Iz•)-based oxidation, reductions were preferentially taken place at the bpy and metal (RuIII/RuII) centers, respectively. Unlike 1 or [2]ClO4 containing one free NH proton at the backface of H-Iz, [1']ClO4 with two H-Iz units could selectively and effectively recognize F-, OAc-, and CN- among the tested anions: F-, OAc-, CN-, Cl-, Br-, I-, SCN-, HSO4-, and Η2PΟ4- in CH3CN via intermolecular NH···anion hydrogen bonding interaction. The difference in the sensing feature between [1']ClO4 and 1/[2]ClO4 could be rationalized by their pKa values of 8.4 and 11.3/10.8, respectively.


Assuntos
Compostos Organometálicos , Rutênio , 2,2'-Dipiridil , Ânions/química , Eletrônica , Indazóis , Ligantes , Nitrogênio , Compostos Organometálicos/química , Prótons , Rutênio/química
3.
Dalton Trans ; 50(28): 9891-9903, 2021 Jul 21.
Artigo em Inglês | MEDLINE | ID: mdl-34196336

RESUMO

The article deals with the sensitive electronic forms in accessible redox states of structurally and spectroscopically authenticated deprotonated 1,2-bis((1H-pyrrol-2-yl)methylene)hydrazine (H2LR, R = H) or 1,2-bis((3,5-dimethyl-1H-pyrrol-2-yl)methylene)hydrazine (H2LR, R = Me), a BODIPY analogue bridged diruthenium complex as a function of varying ancillary ligands. It involved rac-(acac)2RuIII(µ-LR 2-)RuIII(acac)21a, R = H; 1b, R = Me (S = 1, acac = acetylacetonate), rac-[(bpy)2RuII(µ-L2-)RuII(bpy)2](ClO4)2 [2](ClO4)2 (S = 0, bpy = 2,2'-bipyridine) and diastereomeric [(pap)2RuII(µ-L2-)RuII(pap)2](ClO4)2meso-[3a](ClO4)2/rac-[3b](ClO4)2 (S = 0, pap = phenylazopyridine). The crystal structure established the linkage of the conjugated -C5[double bond, length as m-dash]N2-N3[double bond, length as m-dash]C6- central unit with the two terminal deprotonated pyrrole units of coordinated L2-. The bridging L2- in 1a, 1b, [2](ClO4)2, [3b](ClO4)2 and [3a](ClO4)2 was slightly twisted and planar with torsional angles of 41.54°, 42.91°, 37.38°, 35.33° and 0°, respectively, with regard to the central N2-N3 bond. The extent of twisting of the bridge followed an inverse relationship with the RuRu separation: 4.935/4.934 Å 1a/1b < 5.141 Å [2](ClO4)2 < 5.201 Å [3b](ClO4)2 < 5.351 Å [3a](ClO4)2. This is also attributed to the intermolecular ππ/CHπ interactions between the nearby aromatic rings of L and bpy or pap in [2](ClO4)2 or [3](ClO4)2, respectively. The multiple redox steps of the complexes varied appreciably based on the σ-donating (acac) and π-acidic (bpy, pap) characteristics of the ancillary ligands. Experimental (structure, EPR) and theoretical (DFT) evaluation pertaining to the electronic forms of 1n, 2n and 3n demonstrated the preferential involvement of L based frontier orbitals in electron transfer processes even in combination with the redox facile ruthenium ion. This in turn highlighted its redox non-innocent feature as in the case of well-documented metal coordinated quinonoid, formazanate, diimine (bpy), azo (pap) and ß-diketiminate functions.

4.
Chemistry ; 27(17): 5461-5469, 2021 Mar 22.
Artigo em Inglês | MEDLINE | ID: mdl-33459444

RESUMO

Epindolidione (H2 L), a heteroatom-modified analogue of tetracene and a structural isomer of indigo, forms dinuclear complexes with [RuX2 ]2+ , X=bpy (2,2'-bipyridine, [1]2+ ) or pap (2-phenylazopyridine, [2]2+ ), in its doubly deprotonated bridging form µ-L2- . The dications in compounds meso-[1](ClO4 )2 and meso-[2](ClO4 )2 , [X2 Ru(µ-L)RuX2 ](ClO4 )2 , contain five-membered chelate rings N-C-C-O-RuII with π bridged metals at an intramolecular distance of 7.19 Å. Stepwise reversible oxidation and reduction is mainly ligand centered (oxidation: L2- ; reduction: X), as deduced from EPR of one-electron oxidized and reduced intermediates and from UV/Vis/NIR spectroelectrochemistry, supported by TD-DFT calculation results. The results for [1](ClO4 )2 and [2](ClO4 )2 are qualitatively similar to the ones observed with the deprotonated indigo-bridged isomers with their six-membered chelate ring structures, confirming the suitability of both π systems for molecular electronics applications, low-energy absorptions, and multiple electron transfers.

5.
Mol Biol Rep ; 41(7): 4305-12, 2014 Jul.
Artigo em Inglês | MEDLINE | ID: mdl-24574003

RESUMO

Curcin, a type I ribosomal inhibiting protein-RIP, encoded by curcin precursor gene, is a phytotoxin present in Jatropha (Jatropha curcas L.). Here, we report designing of RNAi construct for the curcin precursor gene and further its genetic transformation of Jatropha to reduce its transcript expression. Curcin precursor gene was first cloned from Jatropha strain DARL-2 and part of the gene sequence was cloned in sense and antisense orientation separated by an intron sequence in plant expression binary vector pRI101 AN. The construction of the RNAi vector was confirmed by double digestion and nucleotide sequencing. The vector was then mobilized into Agrobacterium tumefaciens strain GV 3101 and used for tissue culture independent in planta transformation protocol optimized for Jatropha. Germinating seeds were injured with a needle before infection with Agrobacterium and then transferred to sterilized sand medium. The seedlings were grown for 90 days and genomic DNA was isolated from leaves for transgenic confirmation based on real time PCR with NPT II specific dual labeled probe. Result of the transgenic confirmation analysis revealed presence of the gene silencing construct in ten out of 30 tested seedlings. Further, quantitative transcript expression analysis of the curcin precursor gene revealed reduction in the transcript abundance by more than 98% to undetectable level. The transgenic plants are being grown in containment for further studies on reduction in curcin protein content in Jatropha seeds.


Assuntos
Regulação da Expressão Gênica de Plantas , Inativação Gênica , Jatropha/genética , RNA Mensageiro/antagonistas & inibidores , Proteínas Inativadoras de Ribossomos Tipo 1/antagonistas & inibidores , Sementes/genética , Toxinas Biológicas/antagonistas & inibidores , Agrobacterium tumefaciens/genética , Biocombustíveis , Técnicas de Transferência de Genes , Vetores Genéticos , Jatropha/crescimento & desenvolvimento , Jatropha/toxicidade , Folhas de Planta/genética , Folhas de Planta/crescimento & desenvolvimento , Plantas Geneticamente Modificadas/genética , Plantas Geneticamente Modificadas/crescimento & desenvolvimento , RNA Mensageiro/genética , RNA Mensageiro/metabolismo , RNA Interferente Pequeno/genética , RNA Interferente Pequeno/metabolismo , Proteínas Inativadoras de Ribossomos Tipo 1/biossíntese , Proteínas Inativadoras de Ribossomos Tipo 1/genética , Sementes/crescimento & desenvolvimento , Toxinas Biológicas/biossíntese , Toxinas Biológicas/genética
6.
Physiol Mol Biol Plants ; 20(1): 139-42, 2014 Jan.
Artigo em Inglês | MEDLINE | ID: mdl-24554848

RESUMO

Oil-rich seeds of Jatropha curcas are being focussed as a source of bio-diesel. However, prior to its industrial use, a lot of crop improvement efforts are required in Jatropha. Availability of a large number of EST sequences of Jatropha in public domain allow identification of candidate genes for several agronomic characters including oil content in seeds. Here, we have analysed 42,477 ESTs of Jatropha spanning 22.9 Mbp for microsatellites and fatty acid metabolism related sequences. Unigene sequences were built using CAP 3 programme resulted in 12,358 contigs and 5,730 singlets. Nearly, 8 % unigenes showed presence of microsatellites, slightly over-represented compared to their occurrence in ESTs. Most of the microsatellites were either di- or tri-nucleotide repeats, while other categories of tetra-, penta- and hexa-nucleotide repeats together constituted ~4 % of total microsatellites. Assessment of functional relevance of unigenes was carried out using Blast2GO using its default settings. The overall sequence similarity level against sequences in 'nr' database was >80 %. A total of 931 sequences that participated in any of the pathways related to fatty acid or lipid metabolism were found at GO level 6. Among these, GO terms "Fatty acid metabolic process" and "Fatty acid biosynthetic process" were most over-represented. Overall, our work has due relevance in identifying molecular markers for the candidate genes for oil content in Jatropha seeds, and will prove to be an important reference for further studies for identification of trait specific markers in Jatropha.

7.
Springerplus ; 2(1): 117, 2013 Dec.
Artigo em Inglês | MEDLINE | ID: mdl-23543825

RESUMO

Our containment trials have established cold tolerance in Nicotiana tabacum osmotin (Nt Osm) transgenic tomato (Solanum lycopersicum L. cv. Pusa Ruby). Though, the stress tolerance mechanisms have been studied at physio-biochemical levels, molecular mechanisms underlying the tolerant response are still not well studied. Therefore, quantitative transcript expression of Osmotin and other stress responsive genes (CBF1, P5CS and APX) was studied in response to cold (4°C; 2 and 24 h) treatment in the transgenic and wild type tomato plants. The expression analysis revealed differential transcript regulation in the transgenic and wild type plants on the cold exposure. In general, the genes were either earlier induced or the extent of fold change in transcript expression over the respective untreated controls was higher in transgenic than in the wild type plants on cold exposure. The transcript expression data also supported the metabolite analysis on free Proline and ascorbate content. The results thus suggest that constitutive over expression of the Osmotin modulate transcript abundance and functional expression products of the other stress responsive genes thereby, imparting cold tolerance in the transgenic tomato plants.

8.
Mol Biol Rep ; 39(12): 10603-13, 2012 Dec.
Artigo em Inglês | MEDLINE | ID: mdl-23053959

RESUMO

Benefits of seed priming in seedling establishment and tolerance to subsequent stress exposure are well reported. However, the molecular mechanisms underlying the priming mediated benefits are not much discovered. Results of our earlier experiments established that thiourea (TU) seed priming imparts cold tolerance to capsicum seedlings. Therefore, to understand molecular mechanisms underlying priming mediated cold stress tolerance, quantitative transcript expression of stress responsive genes involved in transcript regulation (CaCBF1A, CaCBF1B, Zinc Finger protein, CaWRKY30), osmotic adjustment (PROX1, P5CS, Osmotin), antioxidant defence (CAT2, APX, GST, GR1, Cu/Zn SOD, Mn SOD, Fe SOD), signaling (Annexin), movement of solutes and water (CaPIP1), and metabolite biosynthesis through phenylpropanoid pathway (CAH) was studied in response to cold (4 °C; 4 and 24 h) stress in seedlings grown from the TU primed, hydroprimed and unsoaked seeds. The transcript expression of CaWRKY30, PROX1, Osmotin, Cu/Zn SOD and CAH genes was either higher or induced earlier on cold exposure in thiourea priming than that of hydroprimed and unsoaked over the respective unstressed controls. The results thus suggest that the TU priming modulate expression of these genes thereby imparting cold tolerance in capsicum seedlings.


Assuntos
Adaptação Fisiológica/genética , Capsicum/fisiologia , Temperatura Baixa , Regulação da Expressão Gênica de Plantas/efeitos dos fármacos , Plântula/fisiologia , Estresse Fisiológico/genética , Tioureia/farmacologia , Adaptação Fisiológica/efeitos dos fármacos , Antioxidantes/metabolismo , Capsicum/efeitos dos fármacos , Capsicum/enzimologia , Capsicum/genética , Genes de Plantas/genética , Pressão Osmótica/efeitos dos fármacos , Proteínas de Plantas/genética , Proteínas de Plantas/metabolismo , RNA Mensageiro/genética , RNA Mensageiro/metabolismo , Plântula/efeitos dos fármacos , Plântula/genética , Estresse Fisiológico/efeitos dos fármacos
9.
Plant Sci ; 180(4): 628-33, 2011 Apr.
Artigo em Inglês | MEDLINE | ID: mdl-21421411

RESUMO

Cultivated chickpea (Cicer arietinum) was crossed with its wild relatives from the genus Cicer to transfer favorable genes from the wider gene pool into the cultivar. Post-hybridization barriers led to yellowing and subsequent senescence from as early as 5 days after fertilization, however, the ovules of hybrid embryos could be rescued in vitro. Hybrids were classified as green, partially green or albino. The hybrid status of regenerated plantlets in vitro was confirmed by amplification of nuclear DNA markers. To check whether chloroplast development correlated with plastid DNA inheritance in these crosses, primers were designed using conserved plastid gene sequences from wild and cultivated species. All three possible plastid inheritance patterns were observed: paternal, maternal and biparental. This is the first report of biparental inheritance of plastid DNA in Cicer. No correlation was observed between parental origin of the plastid genome and degree of albinism, indicating that chloroplast development in hybrid genotypes was mostly influenced by nuclear factors.


Assuntos
Cicer/genética , Hibridização Genética , Sequência de Bases , Cicer/anatomia & histologia , Cicer/metabolismo , Cruzamentos Genéticos , DNA de Cloroplastos/química , Genomas de Plastídeos , Genótipo , Dados de Sequência Molecular , Sementes/anatomia & histologia , Sementes/genética , Sementes/metabolismo , Alinhamento de Sequência , Análise de Sequência de DNA
10.
J Palliat Med ; 12(1): 64-70, 2009 Jan.
Artigo em Inglês | MEDLINE | ID: mdl-19284265

RESUMO

BACKGROUND: Underreporting of elder mistreatment by health professionals is a significant problem. PURPOSE: To investigate differences in elder mistreatment reporting threshold between hospice/palliative care (HPC) professionals and Adult Protective Services (APS); explore factors for not reporting elder mistreatment. DESIGN: Cross-sectional questionnaire. SETTING/PARTICIPANTS: Four HPC teams and 42 APS workers in one county. METHODS: Five hypothetical elder mistreatment case vignettes along a spectrum of severity were scored on Likert scales for likelihood of reporting or accepting the cases. HPC professionals were surveyed about their knowledge and beliefs about reporting elder mistreatment. RESULTS: All 42 APS workers and 74% of 73 (n = 54) HPC professionals completed the survey. In all but the most severe case of abuse, APS was more likely to accept reports of elder mistreatment than HPC professionals were in reporting (p < 0.002). HPC professionals had reported a mean of 2.5 (+/-2.8, standard deviation [SD]) cases in the last 5 years. Thirty percent of HPC professionals had suspected cases of elder mistreatment that was not reported in the last 5 years. The median difference between the total number of suspected and reported cases was 2 (+/-4.6, SD). Eleven percent had ethical concerns about reporting and 63% were concerned about practical consequences of reporting. Only 37% correctly identified the reporting agencies that have jurisdiction over abuse that occurs in long-term care. Correct identification of long-term care reporting agencies correlated with whether the HPC professional had training in elder mistreatment (r = 0.35, p = 0.009). Although 96% would report physical abuse that they witnessed, only 63% would report abuse verbalized by the patient. CONCLUSION: There is evidence that significant differences exist in elder mistreatment reporting thresholds between APS and HPC professionals. This finding should encourage HPC professionals to discuss with APS the cases they are unsure about reporting. Future research is need on elder mistreatment in the HPC setting.


Assuntos
Abuso de Idosos , Pessoal de Saúde , Cuidados Paliativos na Terminalidade da Vida , Cuidados Paliativos , Revelação da Verdade , Adulto , Idoso , California , Estudos Transversais , Feminino , Agências de Assistência Domiciliar , Humanos , Masculino , Pessoa de Meia-Idade
SELEÇÃO DE REFERÊNCIAS
DETALHE DA PESQUISA