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1.
Spec Care Dentist ; 2024 Jul 29.
Artigo em Inglês | MEDLINE | ID: mdl-39075774

RESUMO

BACKGROUND AND AIM: Effective strategies and practices can assist in forming future initiatives and policies to improve oral health for individuals with intellectual and developmental disabilities (IDD). This manuscript aims to describe the Tufts Dental Facilities (TDF), a university-state collaboration providing sustained statewide access to comprehensive oral health care for individuals with IDD. PROGRAM DESCRIPTION: The TDF program was established in 1976 as the result of a class action lawsuit to improve medical and dental care for individuals with IDD residing at state institutions in Massachusetts. TDF, A partnership, between Tufts University School of Dental Medicine (TUSDM) and the Commonwealth of Massachusetts, is a network of seven dental clinics strategically positioned across the state. These clinics are specifically designed to meet the oral health needs of individuals with IDD. TUSDM's oral health providers with expertise in special care dentistry deliver comprehensive oral health care for over 6500 individuals with IDD, incorporating supportive care services and access to general anesthesia. Additionally, the program provides training in special care dentistry for dental residents and pre-doctoral dental students. CONCLUSIONS: Leveraging state and university resources, TDF provides a model of a sustainable, long-term system for statewide access to oral health care for individuals with IDD.

2.
J Dent Educ ; 88(6): 765-776, 2024 Jun.
Artigo em Inglês | MEDLINE | ID: mdl-38351882

RESUMO

OBJECTIVES: To create optimal oral and overall community health, dental public health (DPH) specialists must be competent and appropriately skilled to deal with contemporary and emergent public health issues. This study aims to evaluate the current job market demands related to the DPH profession and suggest contemporary skills and qualities that would enable DPH professionals to address emerging issues more effectively in their field. METHODS: A multimethod qualitative study was conducted involving two distinct groups: employers and potential employees. Interviews of stakeholders (employers) representing different job market domains, and a survey was administered to recent DPH residency graduates (employees). Qualitative analysis was applied to the data collected. RESULTS: Employers identified the following skills as crucial for future DPH employees: proficiency in care delivery systems, health informatics, clinical training, leadership, and professional and grant writing skills. Many employers assumed the presence of a clinical component in the residency program. DPH residency graduates emphasized that the most significant barrier to securing positions is the lack of clinical experience within the residency program. CONCLUSIONS: This research highlights skills currently valued by the DPH job market and proposes that DPH specialty training may consider revising its curriculum to include these skills. Implementing such updates would ensure that graduates are well equipped and competitive, thus significantly contributing to the broader objective of attaining optimal oral health and overall well-being of the community.


Assuntos
Odontologia em Saúde Pública , Humanos , Odontologia em Saúde Pública/educação , Currículo , Emprego
3.
J Public Health Dent ; 83(1): 78-86, 2023 03.
Artigo em Inglês | MEDLINE | ID: mdl-36513618

RESUMO

OBJECTIVE: To describe current Dental Public Health diplomates and list the competency domains that diplomates considered either essential or optional elements of their practice. METHODS: The American Board of Dental Public Health administered an electronic survey to active and life member diplomates during September 2021. The survey included 101 items in three sections: (1) Education and Work Experience; (2) Dental Public Health Tasks; and (3) Demographics. The Dental Public Health Tasks section asked individuals how essential work-related tasks were to their current practice. Descriptive analyses were conducted using SAS. RESULTS: The overall response rate was 82.6% (157 eligible of 190 returned). Most respondents were women, 35 to 54 years of age, and either non-Hispanic white or non-Hispanic Asian. Twice as many had DDS or DMD degrees than BDS degrees. The vast majority completed a Dental Public Health residency and received masters level training from an accredited program. About three-fourths worked in the United States and held a U.S. license. More than 37% reported a second doctoral degree and 70% worked in academia. Responses to questions about tasks closely aligned with working in academia and less so with positions related to advocacy, regulation, and program evaluation. CONCLUSIONS: Current diplomates are concentrated in academia. If this trend continues, it may be necessary to restructure the competencies, so training and skills acquisition remain timely and relevant. The specialty may also need to encourage future generations to consider non-academic positions so Dental Public Health remains an impactful component of the public health care system.


Assuntos
Certificação , Conselhos de Especialidade Profissional , Humanos , Estados Unidos , Feminino , Masculino , Saúde Pública , Odontologia em Saúde Pública/educação , Inquéritos e Questionários
4.
Inorg Chem ; 56(5): 2387-2399, 2017 Mar 06.
Artigo em Inglês | MEDLINE | ID: mdl-28186779

RESUMO

Gas-phase reactivity of the copper hydride anions [CuH2]- and [Cu2H3]- toward a range of neutral reagents has been examined via multistage mass spectrometry experiments in a linear ion trap mass spectrometer in conjunction with isotope labeling studies and Density Functional Theory (DFT) calculations. [CuH2]- is more reactive than [Cu2H3]-, consistent with DFT calculations, which show it has a higher energy HOMO. Experimentally, [CuH2]- was found to react with CS2 via hydride transfer to give thioformate (HCS2-) in competition with the formation of the organometallic [CuCS2]- ion via liberation of hydrogen; CO2 via insertion to produce [HCuO2CH]-; methyl iodide and allyl iodide to give I- and [CuHI]-; and 2,2,2-trifluoroethanol and 1-butanethiol via protonation to give hydrogen and the product anions [CuH(OCH2CF3)]- and [CuH(SBu)]-. In contrast, the weaker acid methanol was found to be unreactive. DFT calculations reveal that the differences in reactivity between CS2 and CO2 are due to the lower lying π* orbital of the former, which allows it to accept electron density from the Cu center to form the initial three-membered ring complex intermediate, [H2Cu(η2-CS2)]-. In contrast, CO2 undergoes the barrierless side-on hydride transfer promoted by the high electronegativity of the oxygen atoms. Side-on SN2 mechanisms for reactions of [CuH2]- with methyl iodide and allyl iodide are favored on the basis of DFT calculations. Finally, the DFT calculated barriers for protonation of [CuH2]- by methanol, 2,2,2-trifluoroethanol, and 1-butanethiol correlate with their gas-phase acidities, suggesting that reactivity is mainly controlled by the acidity of the substrate.

5.
Angew Chem Int Ed Engl ; 56(29): 8568-8572, 2017 07 10.
Artigo em Inglês | MEDLINE | ID: mdl-28090725

RESUMO

We report a new approach for the synthesis of heterohexa- and heterodecametalates via the use of non-aqueous, microwave-assisted reaction conditions. The two novel molybdovanadates have been isolated and characterized in the solid and solution states using single-crystal X-ray diffraction, FT-IR, UV/Vis, multinuclear NMR spectroscopy, and ESI-MS. The relative stabilities of the possible structural isomers were probed using dispersion-corrected DFT calculations for both polyoxometalate systems.

6.
Dalton Trans ; 45(48): 19408-19415, 2016 Dec 06.
Artigo em Inglês | MEDLINE | ID: mdl-27882368

RESUMO

ESI/MS of an acetonitrile solution containing a mixture of AgNO3 : bis(dicyclohexylphosphino)methane (dcpm, L) : NaO2CH in a molar ratio of 2 : 1 : 1 gave an abundant peak due to [LAg2(O2CH)]+ and a minor peak assigned as [L2Ag4(O2CH)3]+. When this acetonitrile solution was frozen and layered with diethyl ether and left undisturbed for six days, crystalline material suitable for X-ray crystallography was identified and separated from amorphous solids. Single crystal X-ray diffraction revealed an unusual co-crystal consisting of two discrete tetranuclear silver clusters [(µ2-dcpm)Ag2(µ2-O2CH)(η2-NO3)]2·[(µ2-dcpm)2Ag4(µ2-NO3)4]. While all of the coordinated formates in [LAg2(O2CH)]+ and [L2Ag4(O2CH)3]+ can be decarboxylated in the gas-phase under conditions of collision induced dissociation, only the hydride [LAg2(H)]+ thus formed reacts with formic acid via protonation and liberation of H2 to regenerate to formate, thereby closing a catalytic cycle for the selective decomposition of formic acid.


Assuntos
Complexos de Coordenação/química , Formiatos/química , Prata/química , Cristalização , Cristalografia por Raios X , Gases , Modelos Moleculares , Espectrometria de Massas por Ionização por Electrospray
7.
J Evid Based Dent Pract ; 16(2): 136-8, 2016 Jun.
Artigo em Inglês | MEDLINE | ID: mdl-27449847

RESUMO

ARTICLE TITLE AND BIBLIOGRAPHIC INFORMATION: A large national cohort study of the association between bisphosphonates and osteonecrosis of the jaw in patients with osteoporosis: A nested case-control study. Kwon JW, Park EJ, Jung SY, Sohn HS, Ryu H, Suh HS. JDR Clin Res Suppl 2015;94(9) Suppl 2:213S-9S. SOURCE OF FUNDING: 2014 Pusan National University Research Grant TYPE OF STUDY/DESIGN: Nested matched case-control study.


Assuntos
Conservadores da Densidade Óssea , Difosfonatos , Estudos de Casos e Controles , Estudos de Coortes , Humanos , Osteonecrose , Osteoporose
8.
BMC Health Serv Res ; 16: 309, 2016 07 27.
Artigo em Inglês | MEDLINE | ID: mdl-27460938

RESUMO

BACKGROUND: The programme for fiscal consolidation in Greece has led to income decrease and several changes in health policy. In this context, this study aims to assess how economic crisis affected unmet healthcare needs in Greece. METHODS: Time series analysis was performed for the years 2004 through 2011 using the EU-SILC database. The dependent variable was the percentage of people who had medical needs but did not use healthcare services. Median income, unemployment and time period were used as independent variables. We also compared self-reported unmet healthcare needs drawn from a national survey conducted in pre-crisis 2006 with a similar survey from 2011 (after the onset of the crisis). A common questionnaire was used in both years to assess unmet healthcare needs, including year of survey, gender, age, health status, chronic disease, educational level, income, employment, health insurance status, and prefecture. The outcome of interest was unmet healthcare needs due to financial reasons. Ordinary least squares, as well as logistic regression analysis were conducted to analyze the results. RESULTS: Unmet healthcare needs increased after the enactment of austerity measures, while the year of participation in the survey was significantly associated with unmet healthcare needs. Income, educational level, employment status, and having insurance, private or public, were also significant determinants of unmet healthcare needs due to financial reasons. CONCLUSIONS: The adverse economic environment has significantly affected unmet health needs. Therefore health policy actions and social policy measures are essential in order to mitigate the negative impact on access to healthcare services and health status.


Assuntos
Doença Crônica/economia , Recessão Econômica/estatística & dados numéricos , Necessidades e Demandas de Serviços de Saúde , Doença Crônica/epidemiologia , Emprego/economia , Emprego/estatística & dados numéricos , Feminino , Grécia/epidemiologia , Política de Saúde/economia , Serviços de Saúde/economia , Serviços de Saúde/estatística & dados numéricos , Acessibilidade aos Serviços de Saúde/economia , Acessibilidade aos Serviços de Saúde/estatística & dados numéricos , Humanos , Renda/estatística & dados numéricos , Masculino , Satisfação Pessoal , Autorrelato , Classe Social , Inquéritos e Questionários , Desemprego/estatística & dados numéricos
9.
Nat Commun ; 7: 11746, 2016 06 06.
Artigo em Inglês | MEDLINE | ID: mdl-27265868

RESUMO

Metalloenzymes preorganize the reaction environment to steer substrate(s) along the required reaction coordinate. Here, we show that phosphine ligands selectively facilitate protonation of binuclear silver hydride cations, [LAg2(H)](+) by optimizing the geometry of the active site. This is a key step in the selective, catalysed extrusion of carbon dioxide from formic acid, HO2CH, with important applications (for example, hydrogen storage). Gas-phase ion-molecule reactions, collision-induced dissociation (CID), infrared and ultraviolet action spectroscopy and computational chemistry link structure to reactivity and mechanism. [Ag2(H)](+) and [Ph3PAg2(H)](+) react with formic acid yielding Lewis adducts, while [(Ph3P)2Ag2(H)](+) is unreactive. Using bis(diphenylphosphino)methane (dppm) reshapes the geometry of the binuclear Ag2(H)(+) scaffold, triggering reactivity towards formic acid, to produce [dppmAg2(O2CH)](+) and H2. Decarboxylation of [dppmAg2(O2CH)](+) via CID regenerates [dppmAg2(H)](+). These gas-phase insights inspired variable temperature NMR studies that show CO2 and H2 production at 70 °C from solutions containing dppm, AgBF4, NaO2CH and HO2CH.


Assuntos
Dióxido de Carbono/química , Formiatos/química , Prata/química , Catálise , Descarboxilação , Íons , Ligantes , Teoria Quântica , Soluções , Espectrofotometria Infravermelho , Espectrofotometria Ultravioleta , Termodinâmica
10.
N Y State Dent J ; 82(2): 22-6, 2016 Mar.
Artigo em Inglês | MEDLINE | ID: mdl-27209714

RESUMO

Clinical studies show that fewer than 25% of people who visit a dentist regularly are screened for oral cancer, and that the majority of oral cancers present at an advanced stage, when cure rates are already abysmal. This study explores the current status of oral cancer screening coverage among a variety of insurance providers in New York City. The study focuses on determining the coverage and frequency of the cluster of salient CDT (dental) codes surrounding oral cancer screenings.


Assuntos
Cobertura do Seguro , Seguro Odontológico , Programas de Rastreamento/economia , Neoplasias Bucais/diagnóstico , Codificação Clínica , Citodiagnóstico/economia , Técnica Direta de Fluorescência para Anticorpo/economia , Testes Genéticos/economia , Humanos , Formulário de Reclamação de Seguro , Neoplasias Bucais/economia , Cidade de Nova Iorque , Organizações de Prestadores Preferenciais/economia , Saliva/química , Abandono do Hábito de Fumar/economia
11.
J Phys Chem Lett ; 7(10): 1934-8, 2016 May 19.
Artigo em Inglês | MEDLINE | ID: mdl-27193088

RESUMO

The rhenium dioxide anion [ReO2](-) reacts with carbon dioxide in a linear ion trap mass spectrometer to produce [ReO3](-) corresponding to activation and cleavage of a C-O bond. Isotope labeling experiments using [Re(18)O2](-) reveal that (18)O/(16)O scrambling does not occur prior to cleavage of the C-O bond. Density functional theory calculations were performed to examine the mechanism for this oxygen atom abstraction reaction. Because the spins of the ground states are different for the reactant and product ions ((3)[ReO2](-) versus (1)[ReO3](-)), both reaction surfaces were examined in detail and multiple [O2Re-CO2](-) intermediates and transition structures were located and minimum energy crossing points were calculated. The computational results show that the intermediate [O2Re(η(2)-C,O-CO2)](-) species most likely initiates C-O bond activation and cleavage. The stronger binding affinity of CO2 within this species and the greater instabilities of other [O2Re-CO2)](-) intermediates are significant enough that oxygen atom exchange is avoided.

12.
Org Biomol Chem ; 14(7): 2272-81, 2016 Feb 21.
Artigo em Inglês | MEDLINE | ID: mdl-26795194

RESUMO

Two novel cell-permeable and bacteria-compatible 'turn-on' fluorescent probes, designed to be compatible in a multi-dye system and to fluoresce in the blue region exhibiting emission maxima of 440-490 nm, were synthesized. The profluorescent nitroxide probe (11) was developed to visualize and quantify free radical and redox processes, and the Cu(II)-complexed coumarin-based probe (16a) was developed for NO detection. Confocal laser-scanning microscopy and subsequent digital analysis of Pseudomonas aeruginosa biofilms stained with 11 or 16a determined that free radical and redox processes and NO generation occur predominantly in live cells during normal biofilm growth.


Assuntos
Biofilmes , Cobre/química , Corantes Fluorescentes/farmacocinética , Radicais Livres/análise , Óxido Nítrico/química , Pseudomonas aeruginosa , Biofilmes/crescimento & desenvolvimento , Permeabilidade da Membrana Celular , Cumarínicos/química , Corantes Fluorescentes/síntese química , Corantes Fluorescentes/classificação , Microscopia Confocal , Oxirredução , Coloração e Rotulagem
13.
Nanoscale ; 7(43): 18129-37, 2015 Nov 21.
Artigo em Inglês | MEDLINE | ID: mdl-26470792

RESUMO

Borohydrides react with silver salts to give products that span multiple scales ranging from discrete mononuclear compounds through to silver nanoparticles and colloids. The cluster cations [Ag3(H)(BH4)L3](+) are observed upon electrospray ionization mass spectrometry of solutions containing sodium borohydride, silver(I) tetrafluoroborate and bis(dimethylphosphino)methane (L(Me)) or bis(diphenylphosphino)methane (L(Ph)). By adding NaBH4 to an acetonitrile solution of AgBF4 and L(Ph), cooled to ca. -10 °C, we have been able to isolate the first mixed silver hydride borohydride nanocluster, [Ag3(µ3-H)(µ3-BH4)L(Ph)3]BF4, and structurally characterise it via X-ray crystallography. Combined gas-phase experiments (L(Me) and L(Ph)) and DFT calculations (L(Me)) reveal how loss of a ligand from the cationic complexes [Ag3(H)(BH4)L3](+) provides a change in geometry that facilitates subsequent loss of BH3 to produce the dihydride clusters, [Ag3(H)2Ln](+) (n = 1 and 2). Together with the results of previous studies (Girod et al., Chem. - Eur. J., 2014, 20, 16626), this provides a direct link between mixed silver hydride/borohydride nanoclusters, silver hydride nanoclusters, and silver nanoclusters.

14.
Pediatr Dent ; 37(4): 376-80, 2015.
Artigo em Inglês | MEDLINE | ID: mdl-26314607

RESUMO

PURPOSE: The purpose of this study was to perform a cost-benefit analysis of the age one dental visit for privately insured patients. METHODS: A major insurance company provided claims from various states submitted between 2006-2012. Data provided included numbers of procedures and respective costs from the first visit until age six years. Data was organized into five groups based on age, for which the first D0145/D0150 code was submitted [(1) age younger than one year old; (2) age one or older but younger than two years old; (3) age two or older but younger than three years old; (4) age three or older but younger than four years old; and (5) age four or older but younger than five years old]. The ratio of procedures per child and average costs per child were calculated. RESULTS: Claims for 94,574 children were analyzed; only one percent of these children had their first dental visit by age one. The annual cost for children who had their first dental visit by age one was significantly less than for children who waited until an older age. CONCLUSION: There is an annual cost benefit in establishing a dental home by age one for privately insured patients.


Assuntos
Assistência Odontológica para Crianças/economia , Seguro Odontológico/economia , Setor Privado/economia , Fatores Etários , Pré-Escolar , Resinas Compostas/economia , Análise Custo-Benefício , Coroas/economia , Ligas Dentárias/economia , Amálgama Dentário/economia , Materiais Dentários/economia , Profilaxia Dentária/economia , Restauração Dentária Permanente/economia , Fluoretos Tópicos/economia , Necessidades e Demandas de Serviços de Saúde/economia , Humanos , Lactente , Assistência Centrada no Paciente/economia , Odontologia Preventiva/economia , Aço Inoxidável/economia , Extração Dentária/economia , Estados Unidos
15.
Eur J Mass Spectrom (Chichester) ; 21(3): 557-68, 2015.
Artigo em Inglês | MEDLINE | ID: mdl-26307735

RESUMO

The ion-molecule reactions of the rhenium oxide anions, [ReOx](-) (x = 2 - 4) with the organic substrates methane, ethene, methanol and acetic acid have been examined in a linear ion trap mass spectrometer. The only reactivity observed was between [ReO(2)](-) and acetic acid. Isotope labelled experiments and high-resolution mass spectrometry measurements were used to assign the formulas of the ionic products. Collision-induced dissociation and ion-molecule reactions with acetic acid were used to probe the structures of the mass-selected primary product ions. Density functional theory calculations [PBE0/LanL2DZ6-311+G(d)] were used to suggest possible structures. The three primary product channels observed are likely to arise from the formation of: the metallalactone [ReO(2)(CH(2)CO(2))](-) (m/z 277) and H(2); [CH(3)ReO(2)(OH)](-) (m/z 251) and CO; and [ReO(3)](-) (m/z 235), H(2) and CH(2)CO.

16.
Phys Chem Chem Phys ; 17(19): 12598-607, 2015 May 21.
Artigo em Inglês | MEDLINE | ID: mdl-25899156

RESUMO

Nitroimidazoles are important compounds with chemotherapeutic applications as antibacterial drugs or as radiosensitizers in radiotherapy. Despite their use in biological applications, little is known about the fundamental properties of these compounds. Understanding the ionization reactions of these compounds is crucial in evaluating the radiosensitization potential and in developing new and more effective drugs. Thus, the present study investigates the decomposition of negative and positive ions of 2-nitroimidazole and 4(5)-nitroimidazole using low- and high-energy Collision-Induced Dissociation (CID) and Electron-Induced Dissociation (EID) by two different mass spectrometry techniques and is supported by quantum chemistry calculations. EID of [M+H](+) leads to more extensive fragmentation than CID and involves many radical cleavages including loss of H˙ leading to the formation of the radical cation, M˙(+). The stability (metastable decay) and the fragmentation (high-energy CID) of the radical cation M˙(+) have been probed in a crossed-beam experiment involving primary electron ionization of the neutral nitroimidazole. Thus, fragments in the EID spectra of [M+H](+) that come from further dissociation of radical cation M˙(+) have been highlighted. The loss of NO˙ radical from M˙(+) is associated with a high Kinetic Energy Release (KER) of 0.98 eV. EID of [M-H](-) also leads to additional fragments compared to CID, however, with much lower cross section. Only EID of [M+H](+) leads to a slight difference in the decomposition of 2-nitroimidazole and 4(5)-nitroimidazole.


Assuntos
Elétrons , Modelos Moleculares , Nitroimidazóis/química , Conformação Molecular , Óxido Nítrico/química , Vibração
17.
Phys Chem Chem Phys ; 17(39): 25772-7, 2015 Oct 21.
Artigo em Inglês | MEDLINE | ID: mdl-25827635

RESUMO

The bis(diphenylphosphino)methane (L = Ph2PCH2PPh2) ligated silver deuteride nanocluster dication, [Ag10D8L6](2+), has been synthesised in the condensed phase via the reaction of bis(diphenylphosphino)methane, silver nitrate and sodium borodeuteride in the methanol : chloroform (1 : 1) mixed solvent system. The photoionisation and photofragmentation of this mass-selected cluster were studied using a linear ion trap coupled to the DESIRS VUV beamline of the SOLEIL Synchrotron. At 15.5 eV the main ionic products observed are [Ag10D8L5](2+), [Ag10D8L4](2+), [Ag10D8L6](3+)˙, [Ag9D8L4](2+)˙, and [AgL2](+). The later two products arise from fragmentation of [Ag10D8L6](3+)˙. An analysis of the yields of these product ions as a function of the photon energy reveals the onset for the formation of [AgL2](+) and [Ag9D8L4](2+)˙ is around 2 eV higher than that for ionisation to produce [Ag10D8L5](3+)˙. The onset of ionisation energy of [Ag10D8L6](2+) was determined to be 9.3 ± 0.3 eV from a fit of the yield of the product ion, [Ag10D8L6](3+)˙, as a function of the VUV photon energy. DFT calculations at the RI-PBE/RECP-def2-SVP level of theory were carried out to search for a possible structure of the cluster and to estimate its vertical and adiabatic ionisation energies. The calculated lowest energy structure of the [Ag10D8L6](2+) nanocluster contains a symmetrical bicapped square antiprism as a silver core in which hydrides are located as a mix of triangular faces and edges. Four of the bisphosphines bind to the edges of the cluster core as bidentate ligands, the remaining two bisphosphines bind via a single phosphorus donor atom to each of the apical silver atoms. The DFT calculated adiabatic ionisation energy for this structure is 8.54 eV, in satisfactory agreement with experiment.


Assuntos
Derivados de Benzeno/química , Deutério/química , Metano/análogos & derivados , Compostos Organofosforados/química , Prata/química , Gases/química , Íons/química , Modelos Moleculares , Fotólise , Espectrometria de Massas por Ionização por Electrospray , Raios Ultravioleta
18.
Chemistry ; 20(50): 16626-33, 2014 Dec 08.
Artigo em Inglês | MEDLINE | ID: mdl-25324009

RESUMO

Multistage mass spectrometry and density functional theory (DFT) were used to characterise the small silver hydride nanocluster, [Ag3 H2 L](+) (where L=(Ph2 P)2 CH2 ) and its gas-phase unimolecular chemistry. Collision-induced dissociation (CID) yields [Ag2 HL](+) as the major product while laser-induced dissociation (LID) proceeds via H2 formation and subsequent release from [Ag3 H2 L](+) , giving rise to [Ag3 L](+) as the major product. Deuterium labelling studies on [Ag3 D2 L](+) prove that the source of H2 is from the hydrides and not from the ligand. Comparison of TD-DFT absorption patterns obtained for the optimised structures with action spectroscopy results, allows assignment of the measured features to structures of precursors and products. Molecular dynamics "on the fly" reveal that AgH loss is favoured in the ground state, but H2 formation and loss is preferred in the first excited state S1 , in agreement with CID and LID experimental findings. This indicates favourable photo-induced formation of H2 and subsequent release from [Ag3 H2 L](+) , an important finding in context of metal hydrides as a hydrogen storage medium, which can subsequently be released by heating or irradiation with light.

19.
Chemistry ; 20(43): 14102-11, 2014 Oct 20.
Artigo em Inglês | MEDLINE | ID: mdl-25204640

RESUMO

The first members of a promising new family of hybrid amino acid-polyoxometalates have emerged from a search for modular functional molecules. Incorporation of glycine (Gly) or norleucine (Nle) ligands into an yttrium-tungstoarsenate structural backbone, followed by crystallization with p-methylbenzylammonium (p-MeBzNH3(+)) cations, affords (p-MeBzNH3)6K2(GlyH)[As(III)4(Y(III)W(VI)3)W(VI)44Y(III)4O159(Gly)8(H2O)14]⋅47 H2O (1) and enantiomorphs (p-MeBzNH3)15(NleH)3[As(III)4(Mo(V)2Mo(VI)2)W(VI)44Y(III)4O160(Nle)9(H2O)11][As(III)4(Mo(VI)2W(VI)2)W(VI)44Y(III)4O160(Nle)9(H2O)11] (generically designated 2: L-Nle, 2 a; D-Nle, 2 b). An intensive structural, spectroscopic, electrochemical, magnetochemical and theoretical investigation has allowed the elucidation of site-selective metal substitution and photoreduction of the tetranuclear core of the hybrid polyanions. In the solid state, markedly different crystal packing is evident for the compounds, which indicates the role of noncovalent interactions involving the amino acid ligands. In solution, mass spectrometric and small-angle X-ray scattering studies confirm maintenance of the structure of the polyanions of 2, while circular dichroism demonstrates that the chirality is also maintained. The combination of all of these features in a single modular family emphasizes the potential of such hybrid polyoxometalates to provide nanoscale molecular materials with tunable properties.

20.
Inorg Chem ; 53(14): 7429-37, 2014 Jul 21.
Artigo em Inglês | MEDLINE | ID: mdl-24991699

RESUMO

A bis(diphenylphosphino)methane-ligated trinuclear silver hydride nanocluster, [Ag3((Ph2P)2CH2)3(µ3-H)](BF4)2, featuring three silver(I) ions coordinated to a µ3-hydride, and its deuteride analogue, [Ag3((Ph2P)2CH2)3(µ3-D)](BF4)2, have been isolated and structurally characterized using electrospray ionization mass spectrometry (ESI-MS), X-ray crystallography, NMR and IR spectroscopy. The position of the deuteride in [Ag3((Ph2P)2CH2)3(µ3-D)](BF4)2 was determined by neutron diffraction. ESI-MS of [Ag3L3(µ3-H/D)](BF4)2 [L = ((Ph2P)2CH2)2] produces [Ag3L3(µ3-H/D)](2+) and [Ag3L3(µ3-H/D)(BF4)](+). A rich gas-phase ion chemistry of [Ag3L3(µ3-H/D)](2+) is observed under conditions of collision-induced dissociation (CID) and electron-capture dissociation (ECD). CID gives rise to the following complementary ion pairs: [Ag3L2](+) and [L+(H/D)](+); [Ag2(H/D)L2](+) and [AgL](+); [Ag2(H/D)L](+) and [AgL2](+). ECD gives rise to a number of dissociation channels including loss of the bis(phosphine) ligand, fragmentation of a coordinated bis(phosphine) ligand via C-P bond activation, and loss of a hydrogen (deuterium) atom with concomitant formation of [Ag3L3](+). Under CID conditions, [Ag3L3(µ3-H/D)(BF4)](+) fragments via ligand loss, the combined loss of a ligand and [H,B,F4], and cluster fragmentation to give [Ag2(BF4)L2](+) and [Ag2(L-H)L](+) [where (L-H) = (Ph2P)2CH(-)].


Assuntos
Nanoestruturas , Prata/química , Cristalografia por Raios X , Nêutrons , Espectroscopia de Prótons por Ressonância Magnética
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