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1.
Sci Total Environ ; 895: 164864, 2023 Oct 15.
Artigo em Inglês | MEDLINE | ID: mdl-37331385

RESUMO

The soil-insect interaction has gathered significant attention in the recent years due to its contribution to bio-cementation. Termites, as a group of cellulose-eating insects, alter physical (texture) and chemical (chemical composition) properties of soil. Conversely, physico-chemical properties of soil also influence termite activities. It is vital to understand the soil-termite interaction and their influence on hydraulic properties and shear strength of soil, which are related to a series of geotechnical engineering problems such as ground water recharge, runoff, erosion and stability of slopes. In this study, an attempt has been made to review the latest developments and research gaps in our understanding of soil-termite interaction within the context of geo-environmental engineering. The hydraulic properties and shear strength of termite modified soil were discussed with respect to soil texture, density and physico-chemical composition. The incorporation of hysteresis effect of soil water characteristic curve, and spatio-temporal variations of hydraulic conductivity and shear strength of termite modified soil is proposed to be considered in geotechnical engineering design and construction. Finally, the challenges and future trends in this research area are presented. The expertise from both geotechnical engineering and entomology is needed to plan future research with an aim to promote use of termites as maintenance engineers in geotechnical infrastructure.

2.
Chemosphere ; 307(Pt 1): 135762, 2022 Nov.
Artigo em Inglês | MEDLINE | ID: mdl-35863408

RESUMO

Water quality (WQ) analysis is a critical stage in water resource management and should be handled immediately in order to control pollutants that could have a negative influence on the ecosystem. The dramatic increase in population, the use of fertilizers and pesticides, and the industrial revolution have resulted in severe effects on the WQ environment. As a result, the prediction of WQ greatly helped to monitor water pollution. Accurate prediction of WQ is the foundation of managing water environments and is of high importance for protecting water environment. WQ data presents in the form of multi-variate time-sequence dataset. It is clear that the accuracy of predicting WQ will be enhanced when the multi-variate relation and time sequence dataset of WQ are fully utilized. This article presents the Water Quality Prediction utilising Sparrow Search Optimization with Hybrid Long Short-Term Memory (WQP-SSHLSTM) model. The presented WQP-SSHLSTM model intends to examine the data and classify WQ into distinct classes. To achieve this, the presented WQP-SSHLSTM model undergoes data scaling process to scale the input data into uniform format. Followed by, a hybrid long short-term memory-deep belief network (LSTM-DBN) technique is employed for the recognition and classification of WQ. Moreover, Sparrow search optimization algorithm (SSOA) is utilized as a hyperparameter optimizer of the proposed DBN-LSTM model. For demonstrating the enhanced outcomes of the presented WQP-SSHLSTM model, a sequence of experiments has been performed and the outcomes are reviewed under distinct prospects. The WQP-SSHLSTM model has achieved 99.84 percent accuracy, which is the maximum attainable. The simulation outcomes ensured the enhanced outcomes of the WQP-SSHLSTM model on recent methods.


Assuntos
Poluentes Ambientais , Praguicidas , Pardais , Animais , Ecossistema , Fertilizantes , Memória de Curto Prazo , Qualidade da Água
3.
Sci Rep ; 11(1): 11662, 2021 06 03.
Artigo em Inglês | MEDLINE | ID: mdl-34083560

RESUMO

A simple modified sensor was developed with nicotinic acid hydrazide anchored on graphene oxide (NAHGO), by ultrasonic-assisted chemical route, using hydroxy benzotriazole as a mediator. Structural and morphologies of NAHGO samples were investigated in detail by Fourier-Transform Infrared spectroscopy (FT-IR), Powder X-ray diffraction (P-XRD), Raman spectroscopy, Scanning electron microscopy (SEM), X-ray photoelectron spectroscopy (XPS), and Thermogravimetric analysis (TGA). The detailed morphological examination and electrochemical studies revealed the delaminated sheet with the tube-like structure of NAHGO provided the route for more electroactive surface which influenced the electrooxidation of caffeine with increased current. The electrochemical behaviour of NAHGO on a glassy carbon electrode (GCE) for caffeine detection was demonstrated by employing voltammetric techniques. The influence of scan rate, pH, and concentration on caffeine's peak current was also studied. The NAHGO sensor was employed for the determination of caffeine in imol plus and energy drinks. The detection limit determined was 8.7 × 10-9 M, and the best value was reported so far. The results show that NAHGO modified electrodes are one of the best preferences to establish new, efficient, and reliable analytical tools for the detection of caffeine.

4.
Spectrochim Acta A Mol Biomol Spectrosc ; 236: 118329, 2020 Aug 05.
Artigo em Inglês | MEDLINE | ID: mdl-32299039

RESUMO

In this work, we report the synthesis of two receptors for fluoride ions based on acyl hydrazone, such as N'-[(1Z)-1-(4-fluorophenyl)ethylidene]benzohydrazide (R1) and N'-[(1Z)-1-(2-hydroxyphenyl)ethylidene]benzohydrazide (R2). The receptors R1 and R2 were synthesized from the corresponding ketones and benzoic acid hydrazide and characterized spectroscopically by UV-visible, IR and 1HNMR techniques. The response of R1 and R2 towards different anions was studied colourimetrically in acetonitrile. The receptors exhibited a specific response towards fluoride ions. Further studies of 1:1 composition of receptors, R1/R2:fluoride ions by different spectroscopic techniques such as UV-Visible, IR and 1HNMR spectroscopy indicated the participation of -NH proton of the receptors in the sensing action through the hydrogen bonding. To understand the mechanism, Time-Dependent Density Functional Theory (TD-DFT) studies were done using the CAM-B3LYP/6311G++ (3df,2p) with Grimme's D3BJ empirical dispersion basis set. The studies supported the role of hydrogen bonding interaction of -NH and-OH protons of the receptors with the fluoride ions.

5.
Oral Radiol ; 36(1): 107-111, 2020 01.
Artigo em Inglês | MEDLINE | ID: mdl-30684212

RESUMO

Osteoblastoma is a rare, benign type of osteoblastic tumor. It constitutes approximately 1% of all primary bone tumors. Osteoblastoma most commonly affects the long bones; it very rarely affects the jaw bones. Because of its clinical and histological similarity with other bony tumors, such as osteoid osteoma and fibro-osseous lesions, osteoblastoma is a diagnostic challenge. Very few cases of osteoblastoma involving the maxillofacial region have been reported to date. We herein describe a 15-year-old female patient with osteoblastoma that presented as a palatal swelling of 6 months' duration.


Assuntos
Neoplasias Ósseas , Osteoblastoma , Osteoma Osteoide , Adolescente , Neoplasias Ósseas/diagnóstico por imagem , Feminino , Humanos , Osteoblastoma/diagnóstico , Palato
6.
Artigo em Inglês | MEDLINE | ID: mdl-28748055

RESUMO

Dental anomalies affecting the teeth are relatively common. Simultaneous occurrence of multiple dental abnormalities in a single tooth is uncommon and relatively rare. One such abnormality routinely encountered in dental clinics is the talon cusp. It is also referred to as dens evaginatus, characterized by the presence of an accessory cusp-like structure projecting from the cingulum of anterior teeth. It has an increased predilection for maxillary teeth and permanent dentition. Although numerous cases of talon cusp have been reported in the literature, occurrence of multiple talon cusps in maxillary central incisors has not been found in the literature. This case report highlights the presence of talon cusps in maxillary anterior teeth with multiple impacted supernumerary teeth.

7.
J Clin Diagn Res ; 11(4): ZC89-ZC93, 2017 Apr.
Artigo em Inglês | MEDLINE | ID: mdl-28571271

RESUMO

INTRODUCTION: Oral Lichen Planus (OLP) is a chronic inflammatory mucocutaneous disease affecting the oral cavity which has been associated with severe burning sensation which in turn affects the quality of life of the patients. Currently, the effective treatment of choice remains the use of corticosteroids. The chronicity and recalcitrant nature of the disease demand the long term use of these drugs with ensuing adverse effects. Turmeric and its active ingredient, "curcumin", have been found to have anti-inflammatory, antioxidant and anticancer properties. Hence, this intervention study was done to evaluate the efficacy of curcumin oral gel in the management of oral lichen planus. AIM: The study was conducted to compare the efficacy of 1% curcumin gel with the conventional mid-potent topical corticosteroid, triamcinolone acetonide 0.1% in managing the signs and symptoms of OLP. MATERIALS AND METHODS: An intervention study was conducted on 75 patients diagnosed with OLP divided into three groups, Group 1 (0.1% triamcinolone acetonide oral paste thrice daily in tapering doses), Group 2 (curcumin oral gel thrice daily) and Group 3 (curcumin oral gel six times daily). The patients were analysed for the symptom (burning) and sign (erythema and ulceration) using the numerical rating score and Modified Oral Mucositis Index (MOMI) for a period of three months on a bimonthly basis. The results were analysed using Students t-test and unpaired t-test. RESULTS: Intragroup comparison using paired t-test showed statistically significant reduction in burning sensation (p<0.001) as well as erythema and ulceration (p<0.001) in all the three groups. However, when the three groups were compared Group 1 showed the maximum reduction in burning sensation (77%) and erythema and ulceration (67%). Among the curcuminoid group, increased frequency was found to be more beneficial. CONCLUSION: Curcumin oral gel can bring about clinical improvements in OLP patients; however it cannot be used as a mainstay drug. Instead, it can be used as a maintenance drug after the patient is treated with an initial course of corticosteroids. Further studies with larger sample size and increased drug concentrations may be required.

8.
Indian J Dent Res ; 27(3): 230-5, 2016.
Artigo em Inglês | MEDLINE | ID: mdl-27411649

RESUMO

CONTEXT: Topical corticosteroids are the treatment of choice for oral lichen planus (OLP) due to its potential anti-inflammatory effect. However, chronic nature of OLP often requires long-term and frequent applications, exposing patients to local and systemic side effects. AIM: To detect the systemic absorption of 0.1% triamcinolone acetonide (TAC) through the oral mucosa of patients with OLP. SUBJECTS AND METHODS: This was a pilot pharmacokinetic study carried out in the Department of Oral Medicine and Radiology in collaboration with the Department of Toxicology, over 10 months. A total of twenty patients with OLP were included and advised to apply 0.1% TAC 3 times/day for 2 weeks and 2 times/day for next 2 weeks. Blood samples were obtained on the first and second visits and analyzed for triamcinolone using High pressure liquid chromatography (HPLC). STATISTICAL ANALYSIS USED: Paired t-test was done to compare visual analog scale (VAS) score for burning sensation at the first and second visits, statistically significant if P < 0.05. The baseline demographic data were analyzed using descriptive statistics. RESULTS: Paired t-test was done to compare VAS score for burning sensation at the first and second visits, which turned to being statistically significant (P = 0.001). Although HPLC is an established method for the detection of TAC, none of the study populations showed evidence of steroid (TAC) in the blood sample during 4 weeks of treatment duration. CONCLUSIONS: 0.1% triamcinolone is a relatively safe drug to be used with no systemic absorption in the standard dose regimen for oral lichen palnus.


Assuntos
Glucocorticoides/administração & dosagem , Glucocorticoides/farmacocinética , Líquen Plano Bucal/tratamento farmacológico , Triancinolona Acetonida/administração & dosagem , Triancinolona Acetonida/farmacocinética , Absorção Fisiológica , Administração Tópica , Adulto , Cromatografia Líquida de Alta Pressão , Feminino , Humanos , Masculino , Pessoa de Meia-Idade , Medição da Dor , Projetos Piloto , Resultado do Tratamento
9.
Environ Sci Pollut Res Int ; 22(22): 18066-75, 2015 Nov.
Artigo em Inglês | MEDLINE | ID: mdl-26174983

RESUMO

The present study, the synthesis of silver nanoparticles (AgNPs) at 90 °C temperature using an aqueous extract from Ficus talboti leaf and the antioxidant and antibacterial activities of the AgNPs obtained. The devised method is simple and cost-effective, and it produces spherical AgNPs of size 11.9 ± 2.3 nm. The synthesized AgNPs was characterized as UV-vis spectrum and obtain a peak at 438 nm. The phytochemical study result shows that the secondary metabolites such as alkaloids, saponins, phenolic compounds, tannin, flavonoids, phytosterol, and glycosides may be responsible for reducing as well as capping silver ions into AgNPs. Transmission electron microscopic (TEM) studies of the particles revealed a dominance of spherical particle AgNPs. The face centered cubic structure of the AgNPs was confirmed by X-ray diffraction (XRD) peaks at 111°, 200°, 220°, and 311°; SAED patterns confirms the plane of silver nanoparticle planes with clear circular spots on the selected area electron diffraction (SAED). Elemental analysis was done by energy dispersive X-ray analysis (EDX). In addition, this study evaluated the in vitro antioxidant and antibacterial properties of the biosynthesized AgNPs that were found to be significant.


Assuntos
Antibacterianos/metabolismo , Antioxidantes/metabolismo , Ficus/química , Nanopartículas Metálicas/química , Extratos Vegetais/metabolismo , Folhas de Planta/química , Prata/metabolismo , Antibacterianos/química , Antioxidantes/química , Extratos Vegetais/química , Prata/química
10.
J Clin Exp Dent ; 7(1): e95-9, 2015 Feb.
Artigo em Inglês | MEDLINE | ID: mdl-25810851

RESUMO

OBJECTIVES: The objective of this study was to evaluate the prevalence of different Oral Mucosal diseases in Anxiety and Depression patients. MATERIAL AND METHODS: A hospital based observational Study was conducted in the department of Psychiatry and department of Oral Medicine and Radiology. Patients who were diagnosed with Anxiety or Depression by the psychiatrists using Hamilton Anxiety and Depression scale were subjected to complete oral examination to check for oral diseases like Oral Lichen Planus (OLP), Recurrent Aphthous Stomatitis (RAS), and Burning Mouth Syndrome (BMS). Equal number of control group subjects were also included. RESULTS: In this study statistically significant increase in the oral diseases in patients with anxiety and depression than the control group was recorded. Oral diseases were significantly higher in anxiety patients (20.86%) than in depression (9.04%) and control group patients (5.17%). In anxiety patients, the prevalence of RAS was 12%, OLP was 5.7%, and BMS was 2.87%. In depression patients, the prevalence of RAS was 4.02%, OLP was 2.01% and BMS was 3.01%. In control group the prevalence was 2.2%, 1.33% and 1.62% in RAS, OLP and BMS respectively. RAS and OLP were significantly higher in the younger age group (18-49) and BMS was seen between the age group of 50-77 years in both study and control groups. CONCLUSIONS: The results of the present study showed a positive association between psychological alterations and changes in the oral mucosa, particularly conditions like OLP, RAS and BMS. Thus psychogenic factors like anxiety and depression may act as a risk factor that could influence the initiation and development of oral mucosal diseases. Hence psychological management should be taken into consideration when treating patients with these oral diseases. Key words:Lichen planus, anxiety, depression, burning mouth syndrome, recurrent aphthous stomatitis.

11.
J Korean Assoc Oral Maxillofac Surg ; 40(5): 253-7, 2014 Oct.
Artigo em Inglês | MEDLINE | ID: mdl-25368840

RESUMO

Adenoid cystic carcinoma is a rare epithelial tumour, and comprises about 1% of all malignant tumours of the oral and maxillofacial region. It is a malignant tumour which may develop in the trachea, bronchus, lungs or mammary glands, in addition to the head and neck region. Occurrences in the head and neck are mostly detected in the major salivary gland, oral cavity, pharynx and paranasal sinus where it presents as a slow growing firm nodular swelling. The aim of the article is to highlight the unique presentation of adenoid cystic carcinoma as a solitary ulcer on the floor of the mouth.

12.
Acta Crystallogr Sect E Struct Rep Online ; 70(Pt 5): o532-3, 2014 May 01.
Artigo em Inglês | MEDLINE | ID: mdl-24860344

RESUMO

The title compound, C14H12FN3O, adopts an E conformation with respect to the azomethine bond. The pyridyl and fluoro-benzene rings make dihedral angles of 38.58 (6) and 41.61 (5)° respectively with the central C(=O)N2CC unit, resulting in a non-planar mol-ecule. The inter-molecular inter-actions comprise two classical N-H⋯O and N-H⋯N hydrogen bonds and four non-classical C-H⋯O and C-H⋯F hydrogen bonds. These inter-actions are augmented by a weak π-π inter-action between the benzene and pyridyl rings of neighbouring mol-ecules, with a centroid-centroid distance of 3.9226 (10) Å. This leads to a three-dimensional supra-molecular assembly in the crystal system. The F atom is disordered over two sites in a 0.559 (3): 0.441 (3) ratio, through a 180° rotation of the fluoro-benzene ring.

13.
Acta Crystallogr Sect E Struct Rep Online ; 70(Pt 2): o115, 2014 Feb 01.
Artigo em Inglês | MEDLINE | ID: mdl-24764844

RESUMO

The title compound, C14H12FN3O, adopts an E conformation with respect to the azomethine double bond whereas the N and methyl C atoms are in a Z conformation with respect to the same bond. The ketonic O and azomethine N atoms are cis to each other. The non-planar mol-ecule [the dihedral angle between the benzene rings is 7.44 (11)°] exists in an amido form with a C=O bond length of 1.221 (2) Å. In the crystal, a bifurcated N-H⋯(O,N) hydrogen bond is formed between the amide H atom and the keto O and imine N atoms of an adjacent mol-ecule, leading to the formation of chains propagating along the b-axis direction. Through a 180° rotation of the fluoro-phenyl ring, the F atom is disordered over two sites with an occupancy ratio of 0.632 (4):0.368 (4).

14.
Artigo em Inglês | WPRIM (Pacífico Ocidental) | ID: wpr-201576

RESUMO

Adenoid cystic carcinoma is a rare epithelial tumour, and comprises about 1% of all malignant tumours of the oral and maxillofacial region. It is a malignant tumour which may develop in the trachea, bronchus, lungs or mammary glands, in addition to the head and neck region. Occurrences in the head and neck are mostly detected in the major salivary gland, oral cavity, pharynx and paranasal sinus where it presents as a slow growing firm nodular swelling. The aim of the article is to highlight the unique presentation of adenoid cystic carcinoma as a solitary ulcer on the floor of the mouth.


Assuntos
Brônquios , Carcinoma Adenoide Cístico , Cabeça , Pulmão , Glândulas Mamárias Humanas , Boca , Pescoço , Faringe , Neoplasias das Glândulas Salivares , Glândulas Salivares , Traqueia , Úlcera
15.
Artigo em Inglês | MEDLINE | ID: mdl-23714188

RESUMO

Two novel heterocyclic thiosemicarbazone derivatives have been synthesized, and characterized, by means of spectroscopic and single crystal X-ray diffraction methods. Their chromophoric-fluorogenic response towards anions in competing solvent dimethyl sulfoxide (DMSO) was studied. The receptor shows selective recognition towards fluoride anion. The binding affinity of the receptors with fluoride anion was calculated using UV-visible and fluorescence spectroscopic techniques.


Assuntos
Colorimetria/métodos , Corantes Fluorescentes/química , Fluoretos/análise , Compostos Heterocíclicos/química , Tiossemicarbazonas/química , Absorção , Ânions , Cor , Cristalografia por Raios X , Dimetil Sulfóxido/química , Ligação de Hidrogênio , Conformação Molecular , Espectrometria de Fluorescência , Espectrofotometria Ultravioleta
16.
Acta Crystallogr Sect E Struct Rep Online ; 69(Pt 12): o1828, 2013 Nov 27.
Artigo em Inglês | MEDLINE | ID: mdl-24454252

RESUMO

The asymmetric unit of the title compound, C14H11FN2O, contains two independent mol-ecules, both of which adopt the E conformation with respect to the azomethine C=N bond. The mol-ecules are non-planar, with dihedral angles of 26.92 (12) and 11.36 (11)° between the benzene and phenyl rings. In the crystal, mol-ecules are linked through N-H⋯O=C and N-H⋯N hydrogen bonds into chains along [101]. C-H⋯O contacts link these chains into layers parallel to (001). The three-dimensional crystal packing is stabilized by π-π inter-actions, the shortest separation between the centroids of benzene rings being 3.884 (1) Å.

17.
J Ethnopharmacol ; 130(2): 267-71, 2010 Jul 20.
Artigo em Inglês | MEDLINE | ID: mdl-20457245

RESUMO

AIM OF THE STUDY: Melicope lunu-ankenda (Gaertn.) T.G. Hartley is used in Indian traditional medicine for fever, improving complexion and as a tonic. Previous studies have isolated fungicidal, antifeedant, anti-inflammatory and immunomodulatory compounds from Melicope lunu-ankenda. This study is aimed at the isolation and biological activity screening of potential molecules from the volatile oils and extracts of Melicope lunu-ankenda in the light of traditional applications. MATERIALS AND METHODS: Volatile oil of Melicope lunu-ankenda leaves was isolated by hydrodistillation, characterized by GC-FID, GC-MS, LRI determination, Co-GC and database searches. Major chromene-type compounds in Melicope lunu-ankenda leaf oil, evodione and leptonol, were isolated by preparative TLC and characterized by UV-Vis, IR, 1H-, 13C-, 13C-DEPT NMR and EIMS. They were also isolated from the petroleum ether and acetone extracts of the leaves of Melicope lunu-ankenda by column chromatography in petroleum ether-ethyl acetate. Their contents in leaf oil, leaf and inflorescence extracts were estimated by HPTLC. Antipyretic (Baker's yeast-induced fever test), analgesic (acetic acid-induced writhing, tail immersion assays), anti-inflammatory (carrageenan-induced paw edema) and in vitro antioxidant (DPPH radical, superoxide radical scavenging) activities of evodione and leptonol were tested. RESULTS AND CONCLUSIONS: Gas chromatographic analyses found 50.7% monoterpene hydrocarbons, 0.4% oxygenated monoterpenes, 3.2% sesquiterpene hydrocarbons, 0.7% oxygenated sesquiterpenes and 43.7% chromene-type compounds in Melicope lunu-ankenda leaf oil, with evodione (20.2%) and leptonol (22.5%) as its two major constituents. HPTLC estimations in the petroleum ether, acetone extracts (leaf, inflorescence) and leaf oil found evodione 1.0% (dr. wt., leaf), 1.1% (inflorescence), 0.04% (fr. wt. leaves, leaf oil), and leptonol 0.3% (leaf), 0.3% (inflorescence) and 0.04% (leaf oil). Leptonol (200 mg/kg) showed good antipyretic activity. DPPH radical scavenging assay found moderate activity for leptonol (68.7%, 500 microM), whereas evodione showed near-zero activity. A very similar trend was found in superoxide radical scavenging activity of leptonol (64.5%) and evodione (10.3%), both at 100 microg/ml. Evodione and leptonol showed moderate analgesic activities in acetic acid-induced writhing and tail immersion assays. Moderate anti-inflammatory activity was found for both evodione (59.4%) and leptonol (49.0%) at 100 mg/kg. ETHNOPHARMACOLOGICAL RELEVANCE: Biological activities of evodione and leptonol isolated from Melicope lunu-ankenda justify its traditional uses as a remedy for fever, inflammation and as a tonic.


Assuntos
Analgésicos não Narcóticos/farmacologia , Analgésicos/farmacologia , Anti-Inflamatórios/farmacologia , Antioxidantes/farmacologia , Benzopiranos/farmacologia , Rutaceae , Ácido Acético , Analgésicos/química , Analgésicos/isolamento & purificação , Analgésicos não Narcóticos/química , Analgésicos não Narcóticos/isolamento & purificação , Animais , Anti-Inflamatórios/química , Anti-Inflamatórios/isolamento & purificação , Antioxidantes/química , Antioxidantes/isolamento & purificação , Benzopiranos/química , Benzopiranos/isolamento & purificação , Carragenina , Técnicas de Química Analítica , Modelos Animais de Doenças , Relação Dose-Resposta a Droga , Edema/induzido quimicamente , Edema/prevenção & controle , Febre/microbiologia , Febre/prevenção & controle , Temperatura Alta , Inflamação/induzido quimicamente , Inflamação/prevenção & controle , Camundongos , Estrutura Molecular , Óleos Voláteis , Dor/etiologia , Dor/prevenção & controle , Limiar da Dor/efeitos dos fármacos , Folhas de Planta , Óleos de Plantas , Ratos , Saccharomyces cerevisiae , Superóxidos/química
18.
Spectrochim Acta A Mol Biomol Spectrosc ; 61(1-2): 331-6, 2005 Jan 01.
Artigo em Inglês | MEDLINE | ID: mdl-15556457

RESUMO

An interesting series of heterocyclic base adducts of oxovanadium(IV) complexes have been synthesized by the reaction of vanadium(IV) oxide acetylacetonate with some hydrazones (H(2)L) in the presence of a heterocyclic base 2,2'-bipyridine. The compounds were characterized by analytical and different physico-chemical techniques like IR, electron paramagnetic resonance (EPR) and UV-Vis spectral studies and magnetic studies. The EPR spectra indicate that the free electron is in the d(xy) orbital. The coordination geometry around oxovanadium(IV) in all complexes is octahedral, with one dibasic tridentate ligand L(2-), and one bidentate heterocyclic base. The IR spectra suggest that coordination takes place through azomethine nitrogen and enolate oxygen from the hydrazide moiety and phenolate oxygen. The pyridyl nitrogens of the hydrazones, H(2)L(2) and H(2)L(4) are not involved in the coordination. The molar conductivities show that all the complexes are non-electrolytes. All electronic transitions were assigned. All the compounds are paramagnetic. EPR studies of all compounds suggest axial symmetry. The calculated bonding parameters indicate that in-plane sigma bonding is more covalent than in-plane pi bonding.


Assuntos
2,2'-Dipiridil/química , Hidrazonas/química , Vanadatos/química , Ácidos/química , Cor , Espectroscopia de Ressonância de Spin Eletrônica , Ligantes , Estrutura Molecular , Espectroscopia de Luz Próxima ao Infravermelho , Vanadatos/síntese química
19.
Acta Crystallogr C ; 58(Pt 12): o724-6, 2002 Dec.
Artigo em Inglês | MEDLINE | ID: mdl-12466626

RESUMO

The title molecule, C(13)H(13)N(3)O(3).H(2)O, is in the form of a monohydrated zwitterion. The tetrahydropyridinium ring adopts an envelope conformation and is nearly coplanar with the plane of the imidazoline ring. The water solvate molecule plays an important role as a bridge between zwitterions, forming molecular chains running along the c direction, which are interconnected by N-H.O hydrogen bonds into molecular ribbons. The crystal packing is further stabilized by another N-H.O and one O-H.N hydrogen bond, which interconnect the molecular ribbons.

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