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1.
Transplant Proc ; 54(4): 1167-1168, 2022 May.
Artículo en Inglés | MEDLINE | ID: mdl-35410717

RESUMEN

Several reviews have shown that COVID-19 in children is a relatively mild disease. However, a rare complication affecting children and adolescents after COVID-19 has been identified. Pediatric inflammatory multisystem syndrome temporally associated with COVID-19 (PIMS-TS), which in some cases manifests itself as a hyperinflammatory syndrome with a multiorgan failure, may lead to death. We report a case of a 17-year-old patient who was admitted to the hospital with cardiogenic shock of unknown etiology. The disease was life-threatening, thus necessitating mechanical ventilation, circulatory support, and extracorporeal therapy due to renal and liver dysfunction. The patient tested negative for SARS-CoV-2 Reverse Transcription Polymerase Chain Reaction. Other infectious causes of illness were excluded. However, the patient had a positive IgG antibody test result and high levels of interleukin-6, which helped to diagnose PIMS-TS. Intravenous immunoglobulin and steroid therapies were initiated, unfortunately, with poor outcome. The patient's critical condition, particularly end-stage heart failure, led to mechanical circulatory support implantation and finally orthotopic heart transplantation. After the surgery, the patient's condition improved gradually. PIMS-TS manifests itself with different clinical images and as a state of varying severity, ultimately causing multiorgan dysfunction with shock resembling toxic shock syndrome. Ultimately, myocardial complications of PIMS-TS necessitated heart transplantation in the described patient.


Asunto(s)
COVID-19 , Trasplante de Corazón , Adolescente , COVID-19/complicaciones , Niño , Trasplante de Corazón/efectos adversos , Humanos , SARS-CoV-2 , Síndrome de Respuesta Inflamatoria Sistémica/diagnóstico , Síndrome de Respuesta Inflamatoria Sistémica/etiología
2.
Food Chem ; 385: 132615, 2022 Aug 15.
Artículo en Inglés | MEDLINE | ID: mdl-35290955

RESUMEN

Pea protein isolates contain high-quality plant protein. However, they have sensory drawbacks, notably bitterness and astringency, that have limited their use in commercial foods. This study's aim was thus to identify the main phytochemicals in pea-based samples and to examine associations with sensory attributes. The phytochemical profiles of pea flour, pea protein isolates, and pea protein isolate fractions were characterized via UHPLC-DAD-MS. A total of 48 phytochemicals have been revealed: 6 phenolic acids, 5 flavonoids, and 1 saponin were identified and quantified, while another 9 phenolic acids, 10 flavonoids, and 6 saponins were tentatively identified. The impacts of protein extraction and fractionation were studied. These processes appear to have caused some compound degradation. It was found that 29 compounds were correlated with perceived bitterness and/or astringency. Therefore, these results show that certain phytochemicals can lead to negative sensory attributes in pea-protein-based products.


Asunto(s)
Proteínas de Guisantes , Saponinas , Astringentes , Flavonoides , Harina , Pisum sativum , Fitoquímicos
3.
Waste Manag ; 125: 122-131, 2021 Apr 15.
Artículo en Inglés | MEDLINE | ID: mdl-33684663

RESUMEN

This paper analyzes the fate of 71 priority and emerging organic contaminants all along the treatment trains of sewage sludge treatment facilities in Paris including dewatering by centrifugation, thermal drying and anaerobic digestion. It aimed at proposing and applying a mass balances calculation methodology to each process and pollutant. This data validation strategy demonstrated the complexity to perform representative inlet/outlet sampling and analysis campaigns at industrial scales regarding organic compounds and to propose options to overcome this issue. Centrifugation and drying processes only implied physical mechanisms as phase separation and water elimination. Hence, correct mass balance were expected observed for organic contaminants if sampling and analysis campaigns were representative. This was the case for hydrophobic and neutral compounds. For the other more hydrophilic and charged compounds, the mass balances were scarcely correct. Thus, the conventional sampling and analytical practices used with sludge should be questioned and adapted to better take into account the high heterogeneity of sludge and the evolution of matrix effect within sludge treatment processes on micropollutant determination. For the biological anaerobic digestion process where degradations can occur and removals can be observed, the mass balances were deeply interpreted for 60 contaminants. This process contributed to the elimination above 70% of 21 detected compounds including 16 pharmaceuticals, 2 phthalates, 2 hormones and 1 perfluorinated compound. Removals of domperidone, propranolol, escitalopram, lidocaine, verapamil and cefoperazone under this condition were reported for the first time.


Asunto(s)
Contaminantes Ambientales , Aguas del Alcantarillado , Desecación , Paris , Eliminación de Residuos Líquidos
4.
Sci Total Environ ; 734: 139108, 2020 Sep 10.
Artículo en Inglés | MEDLINE | ID: mdl-32460067

RESUMEN

Organic micropollutants (OMPs) such as polycyclic aromatic hydrocarbons, nonylphenols and pharmaceutical products are ubiquitous in organic wastes generated by most human activities. Those wastes are mainly recycled by land spreading, most often after treatments, such as liming, dewatering, composting or anaerobic digestion. It has been shown essentially at lab scales that biological treatments have an effect on the removal of some OMPs. However, less is known on the role of each step of industrial treatment lines combining physico-chemical and biological treatments on the OMP fate and removal. The present study focuses on the impact of waste treatment on the fate of 53 OMPs along 10 industrial treatment lines treating urban, agricultural wastes or mixtures. The combination of studying a diversity of organic wastes and of OMPs with different characteristics (solubility, ionic charges, hydrophobicity etc.), sampling in situ industrial sites, quantifying native OMP concentrations and looking at each step of complete treatment lines allows for a global and representative view of the OMP fate in the French organic waste treatment sector. Less studied wastes, i.e. territorial mixtures, revealed intermediate OMP contents and compositions, between urban and agricultural wastes. Dewatering and liming, usually dismissed, had a noticeable effect on concentrations. Anaerobic digestion and composting had significant effects on the removal of all pollutant families. Combination of processes enhanced most OMP dissipation. Here we showed for the first time that the process type rather than the waste origin affects dissipation of organic micropollutants. Such data could be used to build and validate dynamic models for the fate of OMPs on solid waste treatment plants.


Asunto(s)
Residuos Sólidos , Anaerobiosis , Compostaje , Humanos , Aguas del Alcantarillado , Eliminación de Residuos Líquidos
5.
Artículo en Inglés | MEDLINE | ID: mdl-19091627

RESUMEN

Paper presents the absorption and photoluminescence of 7-TFM, 6-F, 6-CN, 6-TBu and 6-COOEt derivatives of 1-phenyl-3-methyl-1H-Pyrazolo[3,4-b]quinoline (MPPQ). The measured spectra are compared with the results of the quantum chemical calculations performed by means of the semi-empirical methods (AM1 or PM3) that have been applied either to the equilibrium molecular conformations in vacuo (T=0K) or combined with the MD simulations (T=300 K). The photoluminescent spectra of MPPQ dyes are highly solvatochromic. The emission bands broaden and shift to the red with the increasing of solvent polarity, indicating thus a substantial dipole moment of the excited states. According to the quantum chemical analysis the reason for the strong solvatochromism of MPPQ dyes is related with intramolecular charge transfer (ICT) state. Due to the large dipole moment in the twisted geometry the ICT state is believed to become the lowest excited state in a strongly polar environment. This would explain a considerable solvatochromic shift in the highly polar solvents observed for all MPPQ dyes in the experiment. Such hypothesis is supported by the semi-empirical quantum chemical evaluations.


Asunto(s)
Colorantes/química , Luminiscencia , Pirazoles/química , Quinolinas/química , Solventes/química , Absorción , Simulación por Computador , Modelos Moleculares , Conformación Molecular , Estructura Molecular , Teoría Cuántica , Espectrofotometría , Temperatura
6.
Spectrochim Acta A Mol Biomol Spectrosc ; 73(2): 281-5, 2009 Jul 15.
Artículo en Inglés | MEDLINE | ID: mdl-19321378

RESUMEN

Spectral emission properties of novel 4-aryloxy-1H-pyrazolo[3,4-b]quinolines were investigated. All of the compounds exhibit strong blue luminescence in the solution and in the solid state as well. Pyrazoloquinolines were used as dopants in PVK matrices in electroluminescent devices with ITO/PVK:PQ/Ca/Al light emitting diode configuration.


Asunto(s)
Quinolinas/química , Análisis Espectral , Luminiscencia , Estructura Molecular , Fotoquímica/instrumentación , Fotoquímica/métodos , Pirazoles/química , Análisis Espectral/métodos
7.
Artículo en Inglés | MEDLINE | ID: mdl-17434336

RESUMEN

A series of methoxy (MO) and carboethoxy (CE) derivatives of 1,3-diphenyl-1H-pyrazolo[3,4-b]quinoline ([DPPQ]) are characterized by spectroscopic methods. All dyes show the photoluminescent spectra which are highly solvatochromic. In the case of 6MO[DPPQ] and 6CE[DPPQ] the emission bands are broad and shifted to the red with increasing of solvent polarity whereas the dyes 6MO1pMO[DPPQ] and 6MO13pMO[DPPQ] exhibit a reverse solvatochromism. The large difference between the excited- and state-dipole moments indicates a strong electron transfer effects in all dyes. The EL spectra are obtained for the fabricated OLEDs with a general structure of EL device ITO/PVK:6X[DPPQ]/Ca/Al. The blue emission originating from PVK host matrix appears to be quenched in EL spectra of doped PVK matrix giving rise to emission in blue, blue-green or green spectral regions. The obtained results demonstrate that a series of newly synthesized methoxy and carboethoxy [DPPQ]-derivatives may be considered as promising materials for electroluminescent applications.


Asunto(s)
Electricidad , Luminiscencia , Pirazoles/química , Quinolinas/química , Conformación Molecular , Solventes , Análisis Espectral
8.
Artículo en Inglés | MEDLINE | ID: mdl-17728177

RESUMEN

We report the photovoltaic response of composite films formed by polymer transport matrices poly(3-octylthiophene) (P3OT) and poly(3-decylthiophene) (PDT) with incorporated 1H-pyrazolo[3,4-b]quinoline (PAQ) chromophore (see the first figure). The photovoltage (PV) data were obtained for different substituted PAQ possessing different state dipole moments. The photovoltaic cells were formed between ITO and aluminum electrodes. We found that the PV signal of polymer/PAQ substantially depends on the state dipole moments of the pyrazoloquinoline chromophore. This fact indicates on a possibility of significant enhancement of PV efficiency by appropriate variations of the state dipole moments of chromophore. This results in photoinduced electron transfer from polymer serving as donors to PAQ being the electron acceptor. Despite an efficiency of the PV devices is below 1%, however, it may be substantially enhanced in future varying the chromophore state dipole moments appropriately.


Asunto(s)
Suministros de Energía Eléctrica , Fotoquímica/instrumentación , Polímeros/química , Pirazoles/química , Quinolinas/química , Conductividad Eléctrica , Electroquímica , Luz , Estructura Molecular , Fotoquímica/métodos
9.
Artículo en Inglés | MEDLINE | ID: mdl-16872870

RESUMEN

It has been shown that replacing of O-CH3 substituents in PVK-phenyl derivative chromophores by C-N groups leads to appearance of long-ranged dipole-dipole interactions in the composites including PVK-CN, fullerenes and cyano-biphenyl derivatives. Following quantum chemical calculations it has been demonstrated that interaction of the chromophores with the LC matrices favors dipole-dipole ordering, however it description requires to take into account non-homogenous space charge density distribution. During doping by PVK-CN derivatives phase transition has been found from uniaxial system with pure nematic to the quasi-smectic LC state with the substantially different parameter of ordering. Moreover it was established that during this substitution the switching times drastically jump from millisecond to microsecond regime.


Asunto(s)
Compuestos de Bifenilo/química , Cristales Líquidos/química , Análisis Espectral , Electricidad Estática , Factores de Tiempo
10.
Artículo en Inglés | MEDLINE | ID: mdl-28623840

RESUMEN

Paper reports the synthesis and spectroscopic studies of two novel 1,3-diphenyl pyrazoloquinoxaline (PQX) derivatives with 6-substituted methyl (MePQX) or methoxy (MeOPQX) side groups. The optical absorption and fluorescence emission spectra are recorded in solvents of different polarity. Other photophysical constants, such as the fluorescence lifetime and quantum yield, radiationless and radiative rate constants, electronic transition dipole moments, give complete characterization of MePQX and MeOPQX dyes as materials for potential luminescence or electroluminescence applications. Measured optical absorption and fluorescence emission spectra are compared with the results of quantum-chemical analysis using density functional theory (DFT/TDDFT) methods based on hybrid and long range corrected (LRC) exchange-correlation (xc) functionals in combination with solvation self consistent reaction field model. Comparing to conventional hybrid xc-functionals, the DFT/TDDFT calculations using LRC xc-functionals yield considerably more accurate description of optical absorption and fluorescence emission spectra. The best description of the absorption-emission circle provides the model assuming that optical absorption takes place from preferably flat or weakly twisted molecular conformations in the ground state, as particularly is suggested by the geometrical DFT optimization, whereas the fluorescence emission would be expected from more twisted molecular conformations in the excited state.

11.
Waste Manag ; 59: 379-393, 2017 Jan.
Artículo en Inglés | MEDLINE | ID: mdl-27847230

RESUMEN

This article provides data on the contamination of different kinds of sludge (raw, centrifuged, digested, thermally dried sludge and sludge cake) from Paris conurbation by 71 various pollutants including pharmaceutical products (PHPs), hormones, perfluorinated acids (PFAs), linear alkylbenzene sulfonate (LAS), alkylphenols (APs), phthalates (PAEs), polycyclic aromatic hydrocarbons (PAHs) and polychlorobiphenyls (PCBs). Very high contents of LAS (0.1-10g/kg dry matter - DM) compared to other compounds were found in all types of sludge followed by DEHP (10-100mg/kg DM) and fluoroquinolones (1-100mg/kg DM). APs were measured at intermediary contents in Parisian sludge, lying in the 2-20mg/kg DM range. Finally, hormones, PAHs, PCBs, PAEs, PFAs and the remaining PHPs were all found at contents lower than 1mg/kg DM. For most compounds (PHPs, PFOS, DEHP, PAHs), no significant differences in the micropollutant contents were found for similar types of sludge from different WWTP in Paris, highlighting the homogeneity of sludge contamination in downstream Paris catchment. The variability of concentration is rather high (coefficient of variation >100%) for several PHPs, PFAs or PCBs while it is moderate (<100%) or low (<50%) for fluoroquinolones, hormones, PAHs, APs or LAS. In addition, digestion seems to have a buffer effect as variabilities are lower in digested sludge for PHPs, PFAs, APs and PCBs. During sludge treatment (centrifugation, digestion, thermal drying, sludge conditioning+press filtration), the hormones, LAS, APs, PAHs, DEHP and PCBs concentrations increased, while those of PHPs and PFAs decreased. In the case of digestion, the increase of content can be explained by no pollutant removal or a lower removal than DM removal (concentration phenomenon) whereas the decrease underlines that the compound is more removed than the DM. In any case, these concentration variations presuppose the mechanisms of dissipation that could be attributed to volatilization, biotic or abiotic transformation (complete or with metabolites production), bound residues formation. In addition, data on sludge liquors - centrifuged (CW) and condensed (TDW) waters - from respectively centrifugation and thermal drying were collected. Several hormones, PHPs, PFAs, LAS, PAEs, APs, PCBs and PAHs were quantified in CW and TDW, displaying a transfer through the water removal. The concentrations observed are rather comparable to those found in wastewater.


Asunto(s)
Bifenilos Policlorados/análisis , Hidrocarburos Policíclicos Aromáticos/química , Eliminación de Residuos Líquidos/métodos , Aguas Residuales/química , Contaminantes Químicos del Agua/análisis , Ácidos Alcanesulfónicos/química , Desecación , Hormonas/análisis , Paris , Preparaciones Farmacéuticas/análisis , Aguas del Alcantarillado/química , Temperatura , Purificación del Agua/métodos
12.
Spectrochim Acta A Mol Biomol Spectrosc ; 65(3-4): 833-40, 2006 Nov.
Artículo en Inglés | MEDLINE | ID: mdl-16574472

RESUMEN

Absorption and luminescent spectra of several new synthesized pyrazolo-quinoline possessing different substituents are studied. Absorption spectra of all the considered compounds possess five relatively strong absorption bands at about 430, 320, 270, 253 and about 230 nm. A correlation between the bond lengths between the substituent molecule and mother molecule with the observed spectral shifts was found. Theoretical spectra obtained within semi-empirical quantum chemical AM1 calculation methods seem to be more widened compared to the experimental ones due to electron-vibration interactions. However generally a good coincidence between spectral positions between experimental and calculated spectral peak positions was achieved. The corresponding experimental spectra have an absorption edges situated at about 430 nm which appears in fairly good agreement with quantum chemical simulations, namely for absorption spectra calculated by semi-empirical AM1-method. The red shifts in the experimental luminescence spectra are a consequence of electron-vibration interactions which increase with the effective radius and polarizabilities of the particular substituents.


Asunto(s)
Pirazoles/química , Quinolinas/química , Absorción , Mediciones Luminiscentes , Pirazoles/síntesis química , Quinolinas/síntesis química , Espectrofotometría Ultravioleta
13.
Spectrochim Acta A Mol Biomol Spectrosc ; 64(1): 264-71, 2006 May 01.
Artículo en Inglés | MEDLINE | ID: mdl-16530472

RESUMEN

UV-vis optical spectra of several polythiophene with number of dimers n=1, 5, 10, 15 for cis- and trans-forms were investigated. The study was done theoretically using semi-empirical AM1 (Austin Model 1) and PM3 (Parametric Method 3) methods with the appropriate molecular geometry optimization. The experimental UV-vis absorption spectra were used for verification of the both semi-empirical theoretical models. With the increasing number of dimers a red shift of the absorption edge was observed. Solvent does not play a crucial role on behavior of the absorption spectrum. A comparison of the both semi-empirical methods with the observed experimental absorption spectra is performed. Role of state dipole moments of the investigated polythiophenes in the behavior of the observed UV-vis spectra is discussed. Particular role of pi-conjugated bonds is demonstrated.


Asunto(s)
Polímeros/química , Tiofenos/química , Isomerismo , Estructura Molecular , Espectrofotometría Ultravioleta
14.
Homo ; 67(4): 337-47, 2016 Aug.
Artículo en Inglés | MEDLINE | ID: mdl-27238548

RESUMEN

Information conveyed by facial attractiveness markers such as averageness, bilateral symmetry, and secondary sexual characteristics may play an important adaptive role in human sexual selection. Nonetheless, mate choice also relies on other non-physical characteristics such as, for instance, an individual's age. Women prefer and enter in relationships with older partners, whereas in men the inverse relation is observed. Surprisingly, the link between facial morphological markers of biological quality on the one hand and age disparity between partners on the other hand has been as yet subject of very little research. This study aims to fill this gap. We had used facial photographs and demographic data of heterosexual marriages. Facial cues of biological quality, such as averageness, bilateral symmetry, and sexual dimorphism, were digitally measured using geometric morphometric methods and then associated with spouses' age difference. It turned out that a greater age disparity between spouses correlates, in both partners, with higher scores in facial measures which indicate partners' biological quality. One exception is female facial masculinity - generally regarded as an unattractive marker of a low biological quality - which, too, is associated with higher spouse age disparity. In general, our results show that facial symmetry, averageness, and secondary sexual characteristics may play a role in age-dependent mate choice. We suggest that in marriages where the wife is considerably younger than the husband, wife's greater facial masculinity may increase her perceived age and with it, her perceived maturity.


Asunto(s)
Cara/anatomía & histología , Caracteres Sexuales , Esposos , Adulto , Factores de Edad , Anciano , Cefalometría , Femenino , Humanos , Masculino , Persona de Mediana Edad , Polonia , Conducta Sexual , Estadísticas no Paramétricas
15.
Clin Psychol Rev ; 22(6): 931-44, 2002 Jul.
Artículo en Inglés | MEDLINE | ID: mdl-12214331

RESUMEN

As the demographics of the U.S. population continues to change and become increasingly diverse, clinical psychologists will need to demonstrate their competence in providing culturally appropriate treatments to a wide variety of populations. This article summarizes a comprehensive content analysis of five of the leading scholarly journals in clinical psychology over a 17-year period (1980-1997). Results indicate that only 29.3% of the published articles in the clinical psychology literature included ethnic minority participants. Furthermore, only 5.4% of the articles actually focused specifically on ethnic minority populations. Thus, the clinical psychology literature does not contain adequate coverage of ethnically diverse populations in the U.S., despite their growing numbers. This content analysis provides the field with a baseline for future comparison to determine whether the field in general is responding to the needs of an increasingly diverse society, and to help gauge whether clinical psychologists have the scholarly resources available to assist them with becoming more culturally competent. Implications for the paucity of research and recommendations to ameliorate the problem are discussed.


Asunto(s)
Etnicidad/estadística & datos numéricos , Periodismo Médico/normas , Trastornos Mentales/etnología , Psicología Clínica/estadística & datos numéricos , Diversidad Cultural , Humanos , Trastornos Mentales/terapia , Psicología Clínica/tendencias
16.
Spectrochim Acta A Mol Biomol Spectrosc ; 60(13): 3101-6, 2004 Nov.
Artículo en Inglés | MEDLINE | ID: mdl-15477150

RESUMEN

The results of experimental studies and quantum chemical simulations of the absorption spectra of 1H-pyrazolo[3,4-b]quinoline and its derivatives are presented. The quantum chemical calculations (semi-empirical AM1 and PM3 methods) show similarity in the absorption spectra of 1H-pyrazolo[3,4-b]quinoline and 1,3-dimethyl-1H-pyrazolo[3,4-b]quinoline which are characterized by five strong absorption bands in the spectral range 200-500 nm. A substitution of the methyl groups by at least one phenyl group causes the drastic changes of the absorption spectra mainly within the spectral range 240-370 nm. We attribute these differences to additional molecular double bonding segments C=C of the substituted phenyl groups, i.e. to pi --> pi* transitions. A comparison of measured and the calculated absorption spectra manifests quite satisfactory agreement for all compounds in the part regarding the spectral position of the first oscillator (absorption threshold). At the same time, the measured spectra demonstrate the considerable broadening practically of all absorption bands and even complete damping some of them in the case of phenyl derivatives. The experiments performed with highly and weakly polar organic solvents shows that the solvent effect on the absorption spectra is small. For this reason the discrepancies between the calculated and the measured spectra are attributed to electron-vibronic coupling as well as to rotational dynamics of phenyl rings.


Asunto(s)
Pirazoles/química , Quinolinas/química , Absorción , Ciclohexanos , Furanos , Metilación , Estructura Molecular , Espectrofotometría
17.
Artículo en Inglés | MEDLINE | ID: mdl-22580149

RESUMEN

Paper reports synthesis and spectroscopic properties of four newly synthesized dipyrazolo[3,4-b; 3',4'-e]pyridine (DPP) derivatives. The spectroscopic studies are supplemented by quantum-chemical calculations using DFT/TDDFT/PCM method at the B3LYP/6-31+G(d,p) level of theory. The optical absorption and fluorescence emission processes appear to be weakly dependent on attached side phenyl and/or methyl groups exhibiting in cyclohexane solution the first absorption band (00' transition) in the region of 386-401 nm and the fluorescence band (0'0 transition) in the range of 412-425 nm. The electroluminescence devices (OLEDs) with an active PVK layer doped by DPP dyes have been designed. All the devices exhibit deep blue electroluminescence with the emission maximum being rather weakly dependent on the type of the fluorescent dopant. The obtained results demonstrate that a series of newly synthesized DPP dyes may be considered as perspective blue fluorescent emitters for electroluminescent applications.


Asunto(s)
Electrónica , Luz , Polímeros/química , Pirazoles/química , Piridinas/química , Absorción , Técnicas Electroquímicas , Conformación Molecular , Espectrometría de Fluorescencia
18.
Artículo en Inglés | MEDLINE | ID: mdl-20189450

RESUMEN

Absorption, photo- and electroluminescence spectra of some trityl substituted 1H-pyrazolo[3,4-b]quinolines derivatives (methyl- and phenyl substituted) and fabrication of the single layered organic light emitting diodes are reported. The bulky trityl substituent was introduced to prevent aggregation and crystallization of the dopant in polymer matrix. Role of ground state dipole moments in the observed red Stokes shift, electroluminescent features and photocarrier transport is explored. The maximally achieved brightness about 50Cd/m(2) is observed in the spectral range extending from 443nm up to 462nm. The voltage threshold was varied from 7.8V up to 10V. The brightness-current dependences show an existence of at least two types of carrier injections.


Asunto(s)
Benceno/química , Electricidad , Luz , Metano/química , Fotoquímica/instrumentación , Pirazoles/química , Quinolinas/química , Aldehídos/síntesis química , Aldehídos/química , Electroquímica , Furanos , Mediciones Luminiscentes , Soluciones , Análisis Espectral
19.
Spectrochim Acta A Mol Biomol Spectrosc ; 74(3): 685-90, 2009 Oct 15.
Artículo en Inglés | MEDLINE | ID: mdl-19716761

RESUMEN

The paper presents the measured absorption spectra for several newly synthesized derivatives of bisphenol A based pyrazoloquinoline dimers (BAPQD). The experimental results are compared with quantum chemical calculations performed by semiempirical method AM1 and PM3. Molecular mechanic analysis shows that BAPQD dyes possess by a large number of equilibrium molecular conformations with similar total energies and small energy barriers between these states; thus at room temperature (T=300 K) the molecular dynamics exhibits slow temporal evolution passing a large number of intermediate slightly non-equilibrium conformational states. For this reason the semiempirical quantum chemical methods have been combined with the molecular dynamics simulations. The semiempirical PM3 method exhibits the best agreement with the experimental data, especially in the prediction of the spectral position of the first absorption band (absorption threshold). Taking into account that such good agreement is found for a set of more complex organic systems like BAPQD this may be of substantial interest for chemical engineering which deals with the designing of new efficient organic luminophores for electroluminescent applications.


Asunto(s)
Fenoles/química , Quinolinas/química , Compuestos de Bencidrilo , Dimerización , Modelos Moleculares , Pirazoles/química , Espectrofotometría
20.
J Phys Chem A ; 111(25): 5408-14, 2007 Jun 28.
Artículo en Inglés | MEDLINE | ID: mdl-17539613

RESUMEN

Tautomerism of pyrazolo[3,4-b]quinoline (PQ) was studied using electronic absorption and emission spectroscopies in various polar and nonpolar solvents. The absorption spectra of the tautomers were modeled, and the respective bands were assigned using ab initio quantum mechanical calculations. Temperature-dependent absorption spectra showed the dynamic equilibrium of the two species, which were observed only in aliphatic solvents. The anomalous relative populations of the tautomers were explained by the stabilizing effect of the specific PQ-hydrocarbon interactions. Excited-state intramolecular proton transfer (ESIPT) was proposed to explain the measured fluorescence spectra. Hydrogen bonds that are formed in methanol and benzene were shown to strongly influence the nature of both the absorption and emission spectra.

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