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1.
Sensors (Basel) ; 24(20)2024 Oct 13.
Artigo em Inglês | MEDLINE | ID: mdl-39460078

RESUMO

The advent of connected vehicles holds significant promise for enhancing existing traffic signal and vehicle speed control methods. Despite this potential, there has been a lack of concerted efforts to address issues related to vehicle fuel consumption and emissions during travel across multiple intersections controlled by traffic signals. To bridge this gap, this research introduces a novel technique aimed at optimizing both traffic signals and vehicle speeds within transportation networks. This approach is designed to contribute to the improvement of transportation networks by simultaneously addressing issues related to fuel consumption and pollutant emissions. Simulation results vividly illustrate the pronounced the effectiveness of the proposed traffic signal and vehicle speed control methods of alleviating vehicle delay, reducing stops, lowering fuel consumption, and minimizing CO2 emissions. Notably, these benefits are particularly prominent in scenarios characterized by moderate traffic density, emphasizing the versatility and positive impact of the method across varied traffic conditions.

2.
Angew Chem Int Ed Engl ; : e202414456, 2024 Oct 04.
Artigo em Inglês | MEDLINE | ID: mdl-39365837

RESUMO

Phosphorus mononitride (PN) is a carrier of phosphorus in the interstellar medium. As the simplest derivatives of PN, the radical species HPN• and HNP• have remained elusive. Herein, we report the generation, characterization, and photochemistry of HPN• and HNP• in N2-matrix at 3 K. Specifically, HPN• was formed as a weakly bonded complex with CO in the matrix by 254 nm photolysis of the novel phosphinyl radical HPNCO•. The •NPH-CO complex is extremely unstable, as it undergoes spontaneous isomerization to the lower-energy isomer •PNH-CO through fast quantum mechanical tunneling (QMT) with a half-life of 6.1 min at 3 K. Upon further irradiation at 254 nm, the reverse conversion of •PNH-CO to •NPH-CO along with dehydrogenation to yield PN was observed. The characterization •NPH-CO and •PNH-CO with matrix-isolation IR spectroscopy is supported by D, 15N, and 13C isotope labeling and quantum chemical calculations at the XYGJ-OS/AVTZ level of theory, and the mechanism by hydrogen atom tunneling is consistent with multidimensional instanton theory calculations.

3.
J Ethn Subst Abuse ; : 1-17, 2024 Oct 30.
Artigo em Inglês | MEDLINE | ID: mdl-39475456

RESUMO

This study aims to investigate the mechanism of relapse tendency in male drug abusers and provide empirical evidence for reducing relapse tendency of drug abusers. A survey was conducted on 310 male individuals with drug addiction using Chinese Perceived Stress Scale (CPSS), Simple Coping Style Questionnaire (SCSQ), the Regulatory Emotional Self-Efficacy Scale, and the Relapse Tendency Scale (RTS). (1) Stress is significantly positively correlated with the relapse tendency of individuals with drug addiction; (2) Stress indirectly affects relapse tendency through regulatory emotional self-efficacy; (3) Regulatory emotional self-efficacy can directly and negatively predict relapse tendency, and can also indirectly and negatively predict relapse tendency through coping style. Stress coping theory, tension elimination theory, and the self-administration hypothesis are applicable to explain the tendency to relapse due to stress among compulsory isolated drug abusers in China; Regulatory emotional self-efficacy and coping style play a chain mediating role between stress and relapse tendency of male individuals with drug addiction.

4.
J Phys Chem A ; 128(39): 8305-8311, 2024 Oct 03.
Artigo em Inglês | MEDLINE | ID: mdl-39292919

RESUMO

We report the coexistence of anti-conformers and energetically unfavorable syn-conformers of 2,3-, 2,4-, 2,5-, and 2,6-difluorobenzaldehyde in the gas phase using broadband chirped-pulse Fourier transform microwave (CP-FTMW) spectroscopy. The rotational spectra of monosubstituted 13C isotopologues of the anti-conformers have also been assigned in natural abundance, which were used to derive their vibrationally averaged geometries and semi-experimental equilibrium structures. The energy differences between anti- and syn-conformations are estimated to be 10.9, 11.3, and 12.9 kJ/mol for 2,3-, 2,4-, and 2,5-difluorobenzaldehyde, respectively, at the theoretical level of DLPNO-CCSD(T)/def2-TZVP. Despite the steric repulsion caused by the close proximity between the oxygen atom of the aldehyde group and the ortho-substituted fluorine atom, our experimental results indicate the planarity of the syn-conformations. The frequencies of the large amplitude torsion between the phenyl and aldehyde groups have been estimated by experimental inertial defects, which agree with theoretical calculation results.

5.
J Am Chem Soc ; 146(29): 20494-20499, 2024 Jul 24.
Artigo em Inglês | MEDLINE | ID: mdl-39001838

RESUMO

The photochemistry of nitrous acid (HONO), encompassing dissociation into OH and NO as well as the reverse association reaction, plays a pivotal role in atmospheric chemistry. Here, we report the direct observation of nitrosyl-O-hydroxide (HOON) in the photochemistry of HONO, employing matrix-isolation IR and UV-vis spectroscopy. Despite a barrier of approximately 30 kJ/mol, HOON undergoes spontaneous rearrangement to the more stable HONO isomer through quantum mechanical tunneling, with a half-life of 28 min at 4 K. Kinetic isotope effects and instanton theory calculations reveal that the tunneling process involves the concerted motion of the NO moiety (65.2%) and the hydrogen atom (32.3%). Our findings underscore the significance of HOON as a key intermediate in the photolytic dissociation-association cycle of HONO at low temperatures.

6.
Clin Transl Sci ; 17(7): e13889, 2024 Jul.
Artigo em Inglês | MEDLINE | ID: mdl-39049181

RESUMO

Esophageal and gastric varices (EGV) bleeding is a dangerous side effect of liver cirrhosis. Ascites may affect the effectiveness of carvedilol in preventing EGV rebleeding. A retrospective analysis was done on patients with EGV bleeding who visited our gastroenterology department between January 1, 2015, and October 29, 2020, and were given carvedilol therapy again. Patients were classified based on whether they had ascites. The primary outcome was EGV rebleeding. A total of 286 patients were included, with a median follow-up of 24.0 (19.0-42.0) months, comprising those without ascites (N = 155) and those with ascites (N = 131). The mean age of the patients was 55.15 ± 12.44 years, and 177 (61.9%) of them were men. There were 162 (56.6%) Child-Pugh A grades. The etiology of cirrhosis included 135 (47.2%) cases of hepatitis B. After carvedilol therapy, the patient's portal vein diameter (DPV) was widened (p < 0.05), velocity of portal vein (VPV) was slowed (p = 0.001). During the 1-year follow-up, patients with ascites had a substantially higher rebleeding rate than patients without ascites, with 24 (18.3%) versus 13 (8.4%), respectively (p = 0.013). On univariate analysis, ascites was a risk factor for rebleeding (p = 0.015). The multivariate analysis remained significant after adjusting for age, gender, etiology of cirrhosis, and previous endoscopic treatment, with OR of 2.37 (95% CI: 1.12-5.04; p = 0.025). Ascites was a risk factor for EGV rebleeding in patients undergoing carvedilol therapy. After carvedilol therapy, the patient's DPV was widened and VPV was slowed.


Assuntos
Ascite , Carvedilol , Varizes Esofágicas e Gástricas , Hemorragia Gastrointestinal , Cirrose Hepática , Humanos , Carvedilol/uso terapêutico , Carvedilol/administração & dosagem , Carvedilol/efeitos adversos , Varizes Esofágicas e Gástricas/etiologia , Varizes Esofágicas e Gástricas/diagnóstico , Masculino , Feminino , Pessoa de Meia-Idade , Cirrose Hepática/complicações , Cirrose Hepática/tratamento farmacológico , Ascite/tratamento farmacológico , Ascite/etiologia , Estudos Retrospectivos , Hemorragia Gastrointestinal/etiologia , Hemorragia Gastrointestinal/prevenção & controle , Idoso , Adulto , Resultado do Tratamento , Recidiva , Veia Porta
7.
J Phys Chem Lett ; 15(28): 7327-7334, 2024 Jul 18.
Artigo em Inglês | MEDLINE | ID: mdl-38985131

RESUMO

Methanesulfenic acid, CH3SOH, is a fleeting intermediate in the ·OH-initiated oxidation reactions of dimethyl sulfide (DMS) and dimethyl disulfide (DMDS) in the atmosphere. Herein, we report the characterization and photochemistry of CH3SOH in Ar- and N2-matrices at 10 K. The characterization of CH3SOH with matrix-isolation IR and UV-vis spectroscopy is supported by D and 13C isotope labeling experiments and quantum chemical calculations. In line with the observed absorption at 260 nm for CH3SOH, its photolysis at 254 nm leads to dissociation by yielding the novel water complex H2CS···H2O, which exhibits a five-membered ring structure with intermolecular S···HO and CH···O hydrogen bonding interactions. Upon further irradiation at 193 nm, the H2CS···H2O complex undergoes dehydrogenation to form CS···H2O, which can further convert to HC(O)SH under irradiation at 254 nm. When the photolysis of CH3SOH was performed in an O2-doped Ar-matrix, methanesulfonic acid (MSA, CH3SO3H) was obtained as the oxidation product.

8.
J Psychosoc Nurs Ment Health Serv ; 62(11): 27-34, 2024 Nov.
Artigo em Inglês | MEDLINE | ID: mdl-38950356

RESUMO

PURPOSE: Negative emotions can cause people to make irrational decisions, and decision-making disorders may lead individuals who use methamphetamine (meth) to relapse. Therefore, the current study was performed to investigate whether emotion regulation (ER) can improve negative emotions and thus improve decision-making behavior of individuals who use meth. METHOD: Based on the Iowa Gambling Task, a three-factor mixed experimental design was used to examine the effects of cognitive reappraisal and expressive suppression strategies on negative emotions and decision-making behaviors of 157 individuals who use meth. RESULTS: Cognitive reappraisal and expressive suppression were effective in reducing participants' negative emotions and improving decision-making behaviors. Specifically, two types of ER strategies were effective in improving decision-making abilities of participants with negative emotional distress, and cognitive reappraisal was more effective than expressive suppression. CONCLUSION: Regarding cognitive reappraisal, female participants showed better decision-making behavior than males, which predicts that females who use meth might be more adept at using cognitive reappraisal. This finding suggests that mental health providers should aid substance users in managing their negative emotions and also pay attention to gender differences during the nursing process. [Journal of Psychosocial Nursing and Mental Health Services, 62(11), 27-34.].


Assuntos
Tomada de Decisões , Regulação Emocional , Metanfetamina , Humanos , Masculino , Feminino , Adulto , Transtornos Relacionados ao Uso de Anfetaminas/psicologia , Emoções
9.
J Am Chem Soc ; 146(27): 18699-18705, 2024 Jul 10.
Artigo em Inglês | MEDLINE | ID: mdl-38943601

RESUMO

Carbonyl nitrenes are versatile intermediates that have been extensively characterized; however, their phosphorus analogues remain largely unknown. Herein, we report the observation of a rare example of carbonyl phosphinidene NH2C(O)P, which was generated through the photolytic (193 nm) dehydrogenation of phosphinecarboxamide (NH2C(O)PH2) in a solid N2-matrix at 12 K. The characterization of NH2C(O)P in the triplet ground state with matrix-isolation IR and ultraviolet-visible (UV-vis) spectroscopy is supported by comprehensive isotope labeling experiments (D and 15N) and quantum chemical calculations. Upon visible-light irradiation at 680 nm, NH2C(O)P inserts into dihydrogen by the reformation of NH2C(O)PH2 with concomitant isomerization to the more stable aminophosphaketene (NH2PCO). Additionally, the photoisomerization of NH2C(O)PH2 to NH2C(OH) = PH along with decomposition by yielding hydrogen-bonded complexes HNCO···PH3 and HPCO···NH3 has been observed in the matrix.

10.
Chemistry ; 30(39): e202401397, 2024 Jul 11.
Artigo em Inglês | MEDLINE | ID: mdl-38709557

RESUMO

Aluminium is one of the most abundant metals in the universe and impacts the evolution of various astrophysical environments. Currently detected Al-bearing molecules represent only a small fraction of the aluminium budget, suggesting that aluminium may reside in other species. AlO and AlOH molecules are abundant in the oxygen-rich supergiant stars such as VY Canis Majoris, a stellar molecular factory with 60+ molecules including the prebiotic NC-bearing species. Additional Al-bearing molecules with N, C, O, and H may form in O-rich environments with radiation-accelerated chemistry. Here, we present spectroscopic identification of novel aluminium-bearing molecules composed of [Al, N, C, O, H] and [Al, N, C, O] from the reactions of Al atoms and HNCO in solid argon matrix, which are potential Al-bearing molecules in space. Photoinduced transformations among six [Al, N, C, O, H] isomers and three [Al, N, C, O] isomers, along with their dissociation reactions forming the known interstellar species, have been disclosed. These results provide new insight into the chemical network of astronomically detected Al-bearing species in space.

11.
Phys Chem Chem Phys ; 26(16): 12530-12536, 2024 Apr 24.
Artigo em Inglês | MEDLINE | ID: mdl-38619876

RESUMO

Trifluoroacetylacetone (TFAA) has two enol forms, which can switch to each other via proton transfer. While much attention has been paid to their conformational preferences, the influence of microsolvation on regulating the proton position remains unexplored. Herein, we report the rotational spectra of trifluoroacetylacetone-(water)n (n = 1-3) investigated by chirped pulse Fourier transform microwave spectroscopy in the 2-8 GHz frequency range. Two conformers were identified for both TFAA-H2O and TFAA-(H2O)2, while only one conformer was characterized for TFAA-(H2O)3. The results indicate that water binding on the CH3 side stabilizes the enolF form, whereas water binding on the CF3 side stabilizes the enolH form. The enolF form predominates over the enolH form in these hydrated complexes, which contrasts with the fact that only enolH exists in isolated TFAA. EnolH becomes preferred only when water inserts itself into the intramolecular hydrogen bond. Instanton theory calculations reveal that the proton transfer reaction is dominated by quantum tunneling at low temperatures, leading to the stable existence of only one enol form in each configuration of the hydrated clusters.

12.
Curr Med Chem ; 31(30): 4880-4897, 2024.
Artigo em Inglês | MEDLINE | ID: mdl-38357947

RESUMO

BACKGROUND: Pyroptosis, a cell death process triggered by chemotherapy drugs, has emerged as a highly promising mechanism for combating tumors in recent years. As the lead of new drugs, natural products play an important role in the discovery of anticancer drugs. Compared to other natural products, the medicine food homologous natural products (MFHNP) exhibit a superior safety profile. Among a series of MFHNP molecular skeletons, this study found that only benzylideneacetophenone (1) could induce cancer cell pyroptosis. However, the anti-cancer activity of 1 remains to be improved. AIMS: This study aimed to find a pyroptosis inducer with highly effective antitumor activity by modifying the chalcone structure. METHODS: To examine the effect of the Michael receptor in compound 1 on the induction of pyroptosis, several analogs were synthesized by modifying the Michael acceptor. Subsequently, the anticancer activity was tested by MTT assay, and morphological indications of pyroptosis were observed in human lung carcinoma NCI-H460 and human ovarian cancer CP-70 cell lines. Furthermore, to improve the activity of the chalcone skeleton, the anticancer group 3,4,5- trimethoxyphenyl was incorporated into the phenyl ring. Subsequently, compounds 2-22 were designed, synthesized, and screened in human lung cancer cells (NCI-H460, H1975, and A549). Additionally, a quantitative structure-activity relationship (QSAR) model was established using the eXtreme Gradient Boosting (XGBoost) machine learning library to identify the pharmacophore. Furthermore, both in vitro and in vivo experiments were conducted to investigate the molecular mechanisms of pyroptosis induced by the active compound. RESULTS: α, ß-unsaturated ketone was the functional group of the chalcone skeleton and played a pivotal role in inducing cancer cell pyroptosis. QSAR models showed that the regression coefficients (R2) were 0.992 (A549 cells), 0.990 (NCI-H460 cells), and 0.998 (H1975 cells). Among these compounds, compound 7 was selected to be the active compound. Moreover, compound 7 was found to induce pyroptosis in lung cancer cells by upregulating the expression of CHOP by increasing the ROS level. Furthermore, it effectively suppressed the growth of lung cancer xenograft tumors. CONCLUSION: Compound 7 exhibits antineoplastic activity by regulating the ROS/ER stress/pyroptosis axis and is a kind of promising pyroptosis inducer.


Assuntos
Antineoplásicos , Estresse do Retículo Endoplasmático , Piroptose , Espécies Reativas de Oxigênio , Piroptose/efeitos dos fármacos , Humanos , Antineoplásicos/farmacologia , Antineoplásicos/química , Antineoplásicos/síntese química , Espécies Reativas de Oxigênio/metabolismo , Estresse do Retículo Endoplasmático/efeitos dos fármacos , Animais , Descoberta de Drogas , Linhagem Celular Tumoral , Camundongos , Ensaios de Seleção de Medicamentos Antitumorais , Proliferação de Células/efeitos dos fármacos , Estrutura Molecular , Camundongos Nus , Relação Estrutura-Atividade
13.
Chemistry ; 30(27): e202400490, 2024 May 14.
Artigo em Inglês | MEDLINE | ID: mdl-38421349

RESUMO

The diatomic molecule PH is very reactive, and it serves as the parent compound for phosphinidenes featuring a monovalent phosphorus atom. Herein, we report the characterization and reactivity of a rare hydrogen-bonded complex of PH. Specifically, the molecular complex between PH and HCl has been generated by photolysis of chlorophosphine (H2PCl) at 254 nm in a solid Ar-matrix at 10 K. The IR spectrum of the complex HP⋅⋅⋅HCl and quantum chemical calculations at the UCCSD(T)-F12a/haTZ level consistently prove that the phosphorus atom acts as a hydrogen bond acceptor with a binding energy (D0) of -0.6 kcal mol-1. In line with the observed absorption at 341 nm for the binary complex, the triplet phosphinidene PH undergoes prototype H-Cl bond insertion by reformation of H2PCl upon photoexcitation at 365 nm. However, this hydrogen-bonded complex is unstable in the presence of N2 and HCl, as both molecules prefers stronger interactions with HCl than PH in the observed complexes HP⋅⋅⋅HCl⋅⋅⋅N2 and HP⋅⋅⋅2HCl.

14.
J Am Chem Soc ; 146(8): 5455-5460, 2024 Feb 28.
Artigo em Inglês | MEDLINE | ID: mdl-38359146

RESUMO

Sulfamic acid (NH2SO3H, SFA) is supposed to play an important role in aerosol new particle formation (NPF) in the atmosphere, and its formation mainly arises from the SO3-NH3 reaction system in which weakly bonded donor-acceptor complexes such as SO3···NH3 and isomeric HNSO2···H2O have been proposed as the key intermediates. In this study, we reveal the first spectroscopic observation of HNSO2···H2O in two forms in a solid Ar matrix at 10 K. The major form consists of two intermolecular H bonds by forming a six-membered ring structure with a calculated dissociation energy of 7.6 kcal mol-1 at the CCSD(T)-F12a/aug-cc-pVTZ level of theory. The less stable form resembles SO3···H2O in containing a pure chalcogen bond (S···O) with a dissociation energy of 7.2 kcal mol-1. The characterization of HNSO2···H2O with matrix-isolation IR spectroscopy is supported by D- and 18O-isotope labeling and quantum chemical calculations.

15.
J Am Chem Soc ; 146(6): 4162-4171, 2024 Feb 14.
Artigo em Inglês | MEDLINE | ID: mdl-38306246

RESUMO

Magnesium is an abundant metal element in space, and magnesium chemistry has vital importance in the evolution of interstellar medium (ISM) and circumstellar regions, such as the asymptotic giant branch star IRC+10216 where a variety of Mg compounds bearing H, C, N, and O have been detected and proposed as the important components in the gas-phase molecular clouds and solid-state dust grains. Herein, we report the formation and infrared spectroscopic characterization of the Mg-bearing molecules HMg, [Mg, N, C], [Mg, H, N, C], [Mg, N, C, O], and [Mg, H, N, C, O] from the reactions of Mg/Mg+ and the prebiotic isocyanic acid (HNCO) in the solid neon matrix. Based on their thermal diffusion and photochemical behavior, a complex reactivity landscape involving association, decomposition, and isomerization reactions of these Mg-bearing molecules is developed, which can not only help understand the chemical processes of the magnesium (iso)cyanides in astrochemistry but also provide implications on the presence of magnesium (iso)cyanates in the ISM and the chemical model for the dust grain surface reactions. It also provides a new paradigm of the key intermediate nature of the cationic complexes in the formation of neutral interstellar species.

16.
Expert Rev Gastroenterol Hepatol ; 18(1-3): 5-12, 2024.
Artigo em Inglês | MEDLINE | ID: mdl-38236640

RESUMO

The effectiveness and risks of anticoagulant therapy in cirrhotic patients with non-symptomatic portal vein thrombosis (PVT) remain unclear. We conducted a multicenter, Zelen-designed randomized controlled trial to determine the effectiveness of warfarin in cirrhotic patients with non-symptomatic PVT during a one-year follow-up. In brief, 64 patients were 1:1 randomly divided into the anticoagulation group or the untreated group. The probability of recanalization was significantly higher in the anticoagulation group than those untreated in both ITT analysis (71.9% vs 34.4%, p = 0.004) and PP analysis (76.7% vs 32.4%, p < 0.001). Anticoagulation treatment was the independent predictor of recanalization (HR 2.776, 95%CI 1.307-5.893, p = 0.008). The risk of bleeding events and mortality were not significantly different. A significantly higher incidence of ascites aggravation was observed in the untreated group (3.3% vs 26.5%, p = 0.015). In conclusion, warfarin was proved to be an effective and safe as an anticoagulation therapy for treating non-symptomatic PVT in cirrhotic patients.


Assuntos
Hepatopatias , Trombose Venosa , Humanos , Varfarina/efeitos adversos , Anticoagulantes/efeitos adversos , Veia Porta , Cirrose Hepática/complicações , Cirrose Hepática/diagnóstico , Trombose Venosa/diagnóstico , Trombose Venosa/tratamento farmacológico , Hepatopatias/complicações , Resultado do Tratamento
17.
J Am Chem Soc ; 146(2): 1484-1490, 2024 Jan 17.
Artigo em Inglês | MEDLINE | ID: mdl-38057276

RESUMO

There has been an ongoing debate about whether water enhances or hinders π-π stacking, a phenomenon crucial in various biological and chemical systems. In this study, the influence of water on π-π stacking is investigated by microwave spectroscopic observation of gas-phase hydrated clusters of thiophene dimers. Two isomers of (C4H4S)2-H2O and two isomers of (C4H4S)2-(H2O)2 have been unambiguously identified. These identifications are supported by quantum chemistry calculations and isotopic measurements. In each of these conformations, water molecules are situated between aromatic pairs, forming distinctive interactions. Water molecules engage with thiophene molecules either as hydrogen bond donors through OH···π interactions or as hydrogen bond acceptors through CH···O interactions. The energy decomposition analysis indicates that the bonding pattern of water molecules significantly affects the π···π interactions between aromatic rings. These findings offer valuable structural insights into the role of water in shaping π-π stacking.

18.
Chemistry ; 30(15): e202303283, 2024 Mar 12.
Artigo em Inglês | MEDLINE | ID: mdl-38108540

RESUMO

Phosphinidenes are heavy congeners of nitrenes that have been broadly used as in situ reagents in synthetic phosphorus chemistry and also serve as versatile ligands in coordination with transition metals. However, the detection of free phosphinidenes is largely challenged by their high reactivity and also the lack of suitable synthetic methods, rendering the knowledge about the fundamental properties of this class of low-valent phosphorus compounds limited. Recently, an increasing number of free phosphinidenes bearing prototype structural and bonding properties have been prepared for the first time, thus enabling the exploration of their distinct reactivity from the nitrene analogues. This Concept article will discuss the experimental approaches for the generation of the highly unstable phosphinidenes and highlight their distinct reactivity from the nitrogen analogues so as to stimuate future studies about their potential applications in phosphorus chemistry.

19.
J Phys Chem A ; 127(50): 10591-10599, 2023 Dec 21.
Artigo em Inglês | MEDLINE | ID: mdl-38063135

RESUMO

The elusive 3-fluoro-2H-azirine, cyclic NCH2CF, has been generated through the stepwise decomposition of the acryloyl azide CH2CFC(O)N3 in an N2-matrix at 10 K. The characterization of cyclic NCH2CF with matrix-isolation IR spectroscopy is supported by 15N isotope labeling and the calculations with density functional theory (DFT) at the B3LYP/6-311++G(3df,3pd) level of theory. Upon irradiation at 193 nm, cyclic NCH2CF undergoes ring opening by forming the more stable nitrile isomer CH2FCN. In contrast to the photodecomposition reactions, the high-vacuum flash pyrolysis of CH2CFC(O)N3 in the gas phase at 500 °C yields the Curtius rearrangement product CH2CFNCO along with secondary fragmentation to the atmospherically relevant fluorocarbonyl radical (FCO) and cyanomethyl radical (CH2CN). Calculations on the potential energy profile for the decomposition reactions of CH2CFC(O)N3 demonstrate that the excessive energy, arising from the highly exothermic Curtius rearrangement of the azide, plays a key role in driving further dissociation reactions of CH2CFNCO by overcoming the formidable barriers (>50 kcal mol-1) under the pyrolysis conditions.

20.
J Phys Chem Lett ; 14(46): 10450-10456, 2023 Nov 23.
Artigo em Inglês | MEDLINE | ID: mdl-37962268

RESUMO

The mercaptomethyl radical (·CH2SH) is a higher-energy isomer of the methylthio radical (CH3S·) that has been proposed as an important intermediate in atmospheric and interstellar sulfur chemistry. Herein, we report the spectroscopic identification of ·CH2SH during the UV (365 nm) photolysis of CH3S· in a solid Ar-matrix at 10 K. Upon subsequent irradiation at 266 nm, the dehydrogenation of ·CH2SH to yield CS via the intermediacy of the elusive thioformyl radical (HCS·) has also been observed. The characterization of ·CH2SH and HCS· with matrix-isolation IR and UV-vis spectroscopy is supported by 13C-isotope labeling and quantum chemical calculations at the CCSD(T)-F12a/cc-pVTZ-F12 level using configuration-selective vibrational configuration interaction theory (VCI). The disclosed photochemistry of ·CH2SH provides new insight into understanding the chemical evolution of organosulfur molecules in the interstellar medium (ISM).

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