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1.
Chem Biodivers ; 20(10): e202301049, 2023 Oct.
Artigo em Inglês | MEDLINE | ID: mdl-37728228

RESUMO

Mimosa pudica L. (MP) is well-known plant in traditional medicinal system, especially in India. Unfortunately, leaves of MP are less explored. To determine the food and nutritional value of the neglected part of Mimosa pudica L. (MP), that is MP leaves, phytochemicals and metal ions of MP were quantified by newly developed HPLC and ICPOES-based methods. The content of phytochemicals observed using HPLC analysis for chlorogenic acid, catechin, and epicatechin was 141.823 (±8.171), 666.621 (±11.432), and 293.175 (±12.743) µg/g, respectively. Using GC/MS/MS analysis, fatty acid like oleic acid were identified. In ICP-OES analysis, a significant content of Na, K, Ca, Cu, Fe, Mg, Mn, and Zn was observed. The observed TPC and TFC for MP leaf extracts was 44.327 (±1.041) mg GAE/ g of wt. and 214.217 (±4.372) mg QCE/ g of wt., respectively. The DPPH assay depicted a strong antioxidant activity of MP leaf extracts with IC50 values of 0.796 (±0.081) mg/mL and a TEAC value of 0.0356 (±0.0003). A significant antacid activity (666 mg MP+400 mg CaCO3 >400 mg CaCO3 ≫666 mg Gelusil) of MP leaves was noticed. The methanolic extract of MP leaves demonstrated anti-microbial activity against Staphylococcus aureus (15±2mm), Pseudomonas aeruginosa (12±2mm) and Escherichia coli (10±2mm). In silico studies confirmed the in vitro results obtained for antioxidant, antiacid, and anti-microbial activities. In addition, in silico studies revealed the anti-cancerous and anti-inflammatory potential of the MP leaves. In summary, this study demonstrated the medicinal significance of MP leaves and the conversion of agro-waste or the under-utilized part of MP into pharmaceutical potent materials. Consequently, the present study highlighted that MP leaves alone have medicinal importance with good nutritional utility and possess large promise in the pharma industry along with improving bio-valorization and the environment.

2.
Sensors (Basel) ; 23(14)2023 Jul 15.
Artigo em Inglês | MEDLINE | ID: mdl-37514719

RESUMO

With the development of the Internet of Things (IoT), the number of devices will also increase tremendously. However, we need more wireless communication resources. It has been shown in the literature that non-orthogonal multiple access (NOMA) offers high multiplexing gains due to the simultaneous transfer of signals, and massive multiple-input-multiple-outputs (mMIMOs) offer high spectrum efficiency due to the high antenna gain and high multiplexing gains. Therefore, a downlink mMIMO NOMA cooperative system is considered in this paper. The users at the cell edge in 5G cellular system generally suffer from poor signal quality as they are far away from the BS and expend high battery power to decode the signals superimposed through NOMA. Thus, this paper uses a cooperative relay system and proposes the mMIMO NOMA double-mode model to reduce battery expenditure and increase the cell edge user's energy efficiency and sum rate. In the mMIMO NOMA double-mode model, two modes of operation are defined. Depending on the relay's battery level, these modes are chosen to utilize the system's energy efficiency. Comprehensive numerical results show the improvement in the proposed system's average sum rate and average energy efficiency compared with a conventional system. In a cooperative NOMA system, the base station (BS) transmits a signal to a relay, and the relay forwards the signal to a cluster of users. This cluster formation depends on the user positions and geographical restrictions concerning the relay equipment. Therefore, it is vital to form user clusters for efficient and simultaneous transmission. This paper also presents a novel method for efficient cluster formation.

3.
Sensors (Basel) ; 23(16)2023 Aug 21.
Artigo em Inglês | MEDLINE | ID: mdl-37631830

RESUMO

Hybrid beamforming is a viable method for lowering the complexity and expense of massive multiple-input multiple-output systems while achieving high data rates on track with digital beamforming. To this end, the purpose of the research reported in this paper is to assess the effectiveness of the three architectural beamforming techniques (Analog, Digital, and Hybrid beamforming) in massive multiple-input multiple-output systems, especially hybrid beamforming. In hybrid beamforming, the antennas are connected to a single radio frequency chain, unlike digital beamforming, where each antenna has a separate radio frequency chain. The beam formation toward a particular angle depends on the channel state information. Further, massive multiple-input multiple-output is discussed in detail along with the performance parameters like bit error rate, signal-to-noise ratio, achievable sum rate, power consumption in massive multiple-input multiple-output, and energy efficiency. Finally, a comparison has been established between the three beamforming techniques.

4.
Sensors (Basel) ; 23(15)2023 Jul 27.
Artigo em Inglês | MEDLINE | ID: mdl-37571505

RESUMO

With the onset of 5G technology, the number of users is increasing drastically. These increased numbers of users demand better service on the network. This study examines the millimeter wave bands working frequencies. Working in the millimeter wave band has the disadvantage of interference. This study aims to analyze the impact of different interference conditions on unmanned aerial vehicle use scenarios, such as open-air gatherings and indoor-outdoor sports stadiums. Performance analysis was carried out in terms of received power and path loss readings.

5.
Indian J Microbiol ; 63(3): 337-343, 2023 Sep.
Artigo em Inglês | MEDLINE | ID: mdl-37781019

RESUMO

Foot and mouth disease (FMD) is an extremely contagious disease of cloven-hoofed domesticated and wild animals, resulting in significant economic losses in many parts of the world. FMD virus (FMDV) serotype O is responsible for approximately 70% of global outbreaks. For detection of FMDV antigen or antibody, ELISAs are used worldwide and have several limitations, such as batch-to-batch variation in generating immunobiologicals, high production cost and ethical concerns over animal sacrifice. The use of single domain antibody (sdAb) or variable N-terminal domain of the heavy chain of heavy chain antibody (VHH) found naturally in camels has proven their effectiveness in diagnostics and therapeutics. In the present study, the anti-FMDV serotype O-specific VHH-C1 gene sequence (Accession no. KJ751546) was retrieved from the NCBI database. The gene was synthesized commercially in the pBluescript KS+ cloning vector and expressed in E. coli BL21 (DE3) cells using the pET303/CT-His expression system with a C-terminal 6X-His tag. The expressed sdAb, verified by SDS‒PAGE and western blotting, was purified by Ni-chelate chromatography and used as a coating antibody in double antibody sandwich (DAS) ELISA for FMDV detection and typing. The sdAb exhibited a high binding affinity for FMDV serotype O, without any cross-reactivity toward serotypes A and Asia-1. It exhibited better thermostability up to 85 °C than conventional rabbit polyclonal anti-FMDV sera. The potential of sdAbs thus produced without sacrificing lab animals could be explored for replacing polyclonal sera in DAS-ELISA as well as for developing biosensors or lateral flow devices for FMDV type O detection.

6.
Sensors (Basel) ; 22(11)2022 May 24.
Artigo em Inglês | MEDLINE | ID: mdl-35684607

RESUMO

Optimization of the energy efficiency, fairness, and rates of the system is a vital part of communication systems. Multiple access techniques have a huge potential to enhance such performance parameters. This paper studies the performance of NOMA and OMA systems in a singular cell environment, where the cellular users are distributed randomly, and cooperative relays are considered for better system reliability. The relay nodes forward the signals to the cell-edge users. This paper considers a practical scenario where all the relay equipment is distributed with non-uniform battery power levels. The performance of OMA and NOMA schemes is compared based on the key performance indicators: sum rate, fairness, and energy efficiency. The fairness factor determines fairness in the allocation of resources to all the system's users. The performance of the two schemes is assessed in three deployment scenarios: urban, suburban, and rural scenarios. Through numerical results, it is proved that the performance of the NOMA dominates the OMA scheme.


Assuntos
Redes de Comunicação de Computadores , Noma , Fontes de Energia Elétrica , Humanos , Fenômenos Físicos , Reprodutibilidade dos Testes
7.
Arch Virol ; 166(10): 2847-2852, 2021 Oct.
Artigo em Inglês | MEDLINE | ID: mdl-34363534

RESUMO

Porcine astrovirus (PAstV) is distributed worldwide and has been reported to cause diarrhea in pigs. PAstV belongs to the family Astroviridae and genus Mamastrovirus. PAstVs are divided into five diverse genotypes (PAstV1-PAstV5) on the basis of phylogenetic analysis of a part of the RNA-dependent RNA polymerase (RdRp) gene and the capsid gene. However, knowledge regarding the clinical significance and molecular characteristics of PAstV in Haryana, India, is limited. In this study, we investigated the presence of PAstV by RT-PCR of the partial RdRp gene in 110 rectal swabs collected from diarrheic pigs in different parts of Haryana, India. Of these, 35 samples (31.8%) tested positive for PAstV, with the highest positivity observed among weaning piglets 3 to 9 weeks of age (47.7%, 21/44), followed by fattening pigs 9 to 24 weeks of age (28.5%, 8/28). Phylogenetic analysis of the partial RdRp gene revealed circulation of four different genotypes (PAstV1, PAstV2, PAstV4, and PAstV5) in Haryana, with PAstV1 being the predominant genotype. To the best of our knowledge, this is the first report of the presence of PAstV1 and PAstV5 in the pig population of India. The PAstV sequences revealed high genetic variability and genetic heterogeneity in a relatively confined area.


Assuntos
Infecções por Astroviridae/veterinária , Mamastrovirus/genética , Doenças dos Suínos/virologia , Animais , Infecções por Astroviridae/epidemiologia , Infecções por Astroviridae/virologia , Diarreia/epidemiologia , Diarreia/veterinária , Diarreia/virologia , Variação Genética , Genótipo , Índia/epidemiologia , Mamastrovirus/classificação , Mamastrovirus/isolamento & purificação , Filogenia , RNA Viral/genética , RNA Polimerase Dependente de RNA/genética , Suínos , Doenças dos Suínos/epidemiologia
8.
Aust N Z J Obstet Gynaecol ; 61(2): 188-194, 2021 04.
Artigo em Inglês | MEDLINE | ID: mdl-33577103

RESUMO

Spontaneous subcapsular haematoma of the liver is a rare but life-threatening complication of pregnancy. Prevention of maternal and fetal death requires early identification and specialised management. We report three cases of spontaneous liver haematoma in pregnancy from our institution between 2011 and 2018. We conducted a systematic search of online databases using search terms, ('liver' AND 'pregnancy') AND ('haematoma' OR 'rupture') in order to present a narrative review of the literature and a systematic management framework. Our series is the first Australian report of spontaneous subcapsular haematoma in pregnancy with one fetal death in utero but no maternal deaths. Our systematic search of online databases revealed 45 similar reports in the last ten years. Individual patient data were available for 73 cases. The overwhelming majority of these reports were single cases or small case series. We estimate the mean maternal mortality rate to be 15% but fetal mortality was substantially greater than 15% (although data for neonatal outcomes was incomplete). There was one case report of liver transplantation with excellent maternal and fetal outcome. In the last five years, modern diagnostic techniques and therapeutic options have significantly reduced maternal and fetal mortality. Hepatic artery embolisation is a minimally invasive approach under guidance of imaging and is likely to achieve the best maternal and fetal outcomes. Based on our literature review, we have provided a systematic management framework for spontaneous liver haematoma in pregnancy.


Assuntos
Síndrome HELLP , Hepatopatias , Austrália , Feminino , Síndrome HELLP/terapia , Hematoma/etiologia , Hematoma/terapia , Humanos , Recém-Nascido , Hepatopatias/etiologia , Gravidez
9.
Phys Chem Chem Phys ; 22(5): 3112-3121, 2020 Feb 07.
Artigo em Inglês | MEDLINE | ID: mdl-31967127

RESUMO

The presence of unpaired electrons (radicals) due to structural defects is believed to contribute to the catalytic reactivity of carbon materials. Graphite oxide and graphene oxide (GO) consist of significant structural defects and hence are considered more reactive than graphite and graphene. However, the relationship between their radical content/reactivity and their physical and chemical structures remains unknown, which limits the fabrication of high efficiency carbon-based catalysts. In this work, we progressively oxidize graphite to achieve graphite oxide and GO with different levels of oxidation and different sizes. It is observed that a maximal radical content can be achieved on graphite oxide with a C/O ratio of ca. 3.0 and a thickness of around 50 nm. Such a graphite oxide contains about 45% of π bonds and 38% of oxygenated bonds, respectively. Thinner or thicker sheets have lower radical contents due to over or insufficient oxidation, respectively. Single GO sheets with high radical contents can only be produced through a combination of oxidation and reduction. The catalytic activity of the graphite/graphene oxide for phenol degradation was found to be linearly correlated to their radical contents. The observations are significant for the advancement of carbon-based metal-free catalysis.

10.
Paediatr Anaesth ; 30(1): 25-33, 2020 01.
Artigo em Inglês | MEDLINE | ID: mdl-31733116

RESUMO

BACKGROUND AND OBJECTIVES: Epidural analgesia is an effective, established perioperative intervention in all age-groups. In children, however, epidural-related data are limited compared to the adult population. The aim of this study was to examine the use of pediatric epidural analgesia in our institution and, thereby, add to the existing data pool. METHODOLOGY: Patients who received epidural analgesia as part of their perioperative management between 1996 and 2016 at Great Ormond Street Hospital, London, UK, were studied to determine how epidural practice has changed over time, associated incidence of serious adverse events, complications, and patient/parent satisfaction. Epidural use and monitoring were in accordance with standard hospital protocols. Data were prospectively collected and entered into a secure database by trained personnel. These data were subsequently extracted for retrospective analysis. RESULTS: A total of 3876 patients were included. The median age was 4.4 years (range 1 day to 20 years), and the median weight was 20.3 kg. Across all age-groups, the lumbar region was the most common site of epidural insertion while urology (42.2%) and general surgery (37.3%) were the specialities for which it was most utilized. Over the study period, the number of epidurals performed declined while the number of surgical procedures performed simultaneously increased. The infusate most commonly used was local anesthetic with preservative-free morphine (71.9%). In 923 (23.2%) patients, systemic opioids were additionally used for analgesic management by means of patient-controlled analgesia or nurse-controlled analgesia. There was one serious adverse event in the form of permanent nerve injury, giving an overall incidence of approximately 1:3800. Other complications included postoperative nausea and vomiting (35.9%), urinary retention (4.4%), and pruritus (31%). Overall global satisfaction with the service was generally high, with 95% providing a rating of "very good" or "good." CONCLUSION: This study evaluated two decades of epidural practice in our institution. Epidural analgesia remains a safe, effective option for postoperative analgesia, but its use has declined over time, and this trend is likely to continue. Rates of serious adverse events and complications were low and comparable to those published in other similar studies. Global satisfaction among patients/parents remains high.


Assuntos
Analgesia Epidural/efeitos adversos , Analgesia Epidural/tendências , Adolescente , Analgesia Epidural/estatística & dados numéricos , Analgésicos/administração & dosagem , Analgésicos/efeitos adversos , Anestesia Local/efeitos adversos , Criança , Pré-Escolar , Estudos de Coortes , Feminino , Hospitais Pediátricos/tendências , Humanos , Lactente , Recém-Nascido , Londres , Região Lombossacral , Masculino , Náusea/induzido quimicamente , Período Perioperatório , Complicações Pós-Operatórias/induzido quimicamente , Prurido/induzido quimicamente , Insuficiência Respiratória/induzido quimicamente , Estudos Retrospectivos , Retenção Urinária , Vômito/induzido quimicamente , Adulto Jovem
11.
Intern Med J ; 49(7): 911-914, 2019 07.
Artigo em Inglês | MEDLINE | ID: mdl-31295788

RESUMO

Transition from paediatric to adult diabetes care can be associated with a deterioration in metabolic control and hospitalisation. This was a retrospective review (2012-2016) of medical records of all patients attending a transition diabetes clinic in a teaching hospital with paediatric and adult diabetes on the same site. Among the 91/102 (89.2%) patients with type 1 diabetes, mean age at first visit was 19 ± 2 years, last body mass index was 25.2 ± 4.7 kg/m2 , diabetes duration was 11 ± 6 years and 22 (24%) used continuous subcutaneous insulin infusions. Loss to follow-up was 15 (14.7%). Mental health issues were common (59%), as were prior pregnancies (23%) and diabetic ketoacidosis since diagnosis (39%). Those with diabetic ketoacidosis had a higher mean glycated haemoglobin (70 ± 19 vs 86 ± 25 mmol/mol or 8.6 ± 1.7 vs 10.0 ± 2.3%; P = 0.001), fewer clinic attendances (8 ± 5 vs 5 ± 4; P = 0.008) and fewer years in clinic (1.8 ± 1.7 vs 2.3 ± 1.4; P = 0.114). Our data suggest that investment in joint approaches with mental health services should be considered.


Assuntos
Diabetes Mellitus Tipo 1/diagnóstico , Diabetes Mellitus Tipo 1/psicologia , Cetoacidose Diabética/diagnóstico , Cetoacidose Diabética/psicologia , Serviços de Saúde Mental , Adolescente , Diabetes Mellitus Tipo 1/sangue , Cetoacidose Diabética/sangue , Feminino , Humanos , Sistemas de Infusão de Insulina/psicologia , Sistemas de Infusão de Insulina/tendências , Masculino , Serviços de Saúde Mental/tendências , Estudos Retrospectivos , Adulto Jovem
12.
Chemistry ; 24(55): 14668-14678, 2018 Oct 01.
Artigo em Inglês | MEDLINE | ID: mdl-30277280

RESUMO

Supramolecular assembly of chromophores with inherent resistance to aggregation-induced self-quenching is significant to applications such as chemical sensing and organic light emitting diodes (OLEDs). In this work, molecular gels with aggregation-induced emission (AIE) are constructed by simply coassembling AIE chromophores (electron donor or acceptor) with a nonfluorescent molecular gelator. The binary gels are fluorescent even at very low concentrations of the AIE chromophores, indicating that the rotation of their aromatic cores is restricted in the gel network. In tertiary gels, the fluorescence of the donor chromophore can be efficiently reduced by the acceptor chromophore through a combination of static and dynamic quenching process, via charge transfer from the donor to the acceptor. This work demonstrates a convenient approach to fabricate a supramolecular charge transfer system using an AIE donor and acceptor.


Assuntos
Materiais Biomiméticos/química , Aminopiridinas/química , Ciclopentanos/química , Dimetil Sulfóxido/química , Géis/química , Microscopia Confocal , Microscopia Eletrônica de Varredura , Ácidos Pentanoicos/química , Teoria Quântica , Espectrofotometria , Estilbenos/química , Temperatura , Raios Ultravioleta , Difração de Raios X
13.
J Assoc Physicians India ; 66(10): 11-12, 2018 Oct.
Artigo em Inglês | MEDLINE | ID: mdl-31317704

RESUMO

Diabetes mellitus a disease with various macro and micro vascular complications due to its various metabolic dysregulations, is well known to involve lungs in long run in both type 1 and 2 diabetes mellitus, causing tremendous burden on health care system. Common simple lung function tests alone are likely to underestimate the prevalence and degree of lung dysfunction in diabetes, but newer noninvasive tests of lung mechanical function provide a more sensitive assessment of peripheral airway function, hence by establishing a marker and risk factors for pulmonary involvement in diabetic individuals, cases with high risk for pulmonary involvement can be found before hand and proper medical therapy can be started for primary prophylaxis of same, Hence in this study we tried to find out any correlation between serum adiponectin levels and pulmonary dysfunction in patients of type 2 diabetes mellitus, which shows a significant role of adiponectin as early marker of the disease with p value of 0.04, the decrease in serum adiponectin level is also associated with more severe disease, hence adiponectin levels can be used as early markers of pulmonary dysfunction in diabetic patients.


Assuntos
Adiponectina/sangue , Doenças Cardiovasculares , Complicações do Diabetes/epidemiologia , Diabetes Mellitus Tipo 2/epidemiologia , Biomarcadores , Complicações do Diabetes/sangue , Diabetes Mellitus Tipo 1 , Diabetes Mellitus Tipo 2/sangue , Humanos
14.
Chemistry ; 23(16): 3950-3956, 2017 Mar 17.
Artigo em Inglês | MEDLINE | ID: mdl-28217844

RESUMO

The induction of chirality in supramolecular structures through hierarchical self-assembly of achiral compounds and the control of their handedness are closely related to the evolution of life and the chiral amplification found in nature. Herein, it is shown that the combination of achiral tetraphenylethylene, an aggregation-induced emission (AIE)-active luminophore bearing four alkyl chains with an odd or even number of carbon atoms via an amide linkage in the molecular structure allows the induction and control of supramolecular chirality in well-defined helical superstructures by controlling the solvent composition and polarity. In particular, right-handed supramolecular structures were produced for an even number of carbon atoms in the alkyl chains, whereas an odd number led to the assembly of left-handed superstructures. The twisted superstructure was visualised by SEM, and circular dichroism was used to observe chirality in the assembly. These controlled assemblies of AIE-active molecules are of potential practical value, such as templates for helical crystallisation, catalysis and formation of chiral mechanochromic luminescent superstructures.

15.
Langmuir ; 32(46): 12175-12183, 2016 11 22.
Artigo em Inglês | MEDLINE | ID: mdl-27759394

RESUMO

Coassembly of molecules can produce materials with improved properties and functionalities. To this end, achieving a molecular level understanding of the interactions governing the coassembly is essential. In this work, two molecular gelators with significantly different structures and main intermolecular forces for assembly were coassembled. The elastic moduli of the hybrid gels are more than 1 order of magnitude higher than those of the gels formed by the individual gelators, showing an obvious synergistic effect. The interactions between the gelators were investigated with confocal microscopy and both one-dimensional and two-dimensional nuclear magnetic resonance. It was found that the two gelators coassemble to form fibers due to the nonspecific van der Waals interactions between their alkyl chains and the specific interactions between their functional groups. Switching from one gelator-dominated fiber network to the other gelator-dominated fiber network was achieved at a critical molar ratio of the gelators. The two gelators serve as additives of each other to tune the nucleation and growth of the fiber networks. The observations of this work are significant to the development of materials with improved properties by coassembly of different molecules.

16.
J Org Chem ; 81(10): 4012-9, 2016 05 20.
Artigo em Inglês | MEDLINE | ID: mdl-27088459

RESUMO

Electrophilic activation of alkynylphosphine oxides and phosphonates provides a novel approach to the synthesis of P-substituted and P-centered heterocycles. Iodocyclization affords a heteroaryl iodide that can, among other things, be used in reiterative alkyne coupling and iodocyclization to give cyclic phosphonates and other cyclization reactions to give π-rich P-heterocycles.

17.
Aust Prescr ; 39(2): 40-6, 2016 Apr.
Artigo em Inglês | MEDLINE | ID: mdl-27340321

RESUMO

Osteoporotic fractures are common resulting in increased morbidity and mortality. Exercise can help prevent osteoporosis. It can also benefit patients with osteoporosis, but the exercises must be tailored to the patient. Most Australians should be able to obtain adequate calcium in their diet and vitamin D from the sun. Supplements may be needed in some patients and they are recommended for use with other drugs for osteoporosis. Bisphosphonates, and in some patients denosumab, are first-line drugs for osteoporosis. Raloxifene and strontium ranelate can be considered in patients who cannot take bisphosphonates or denosumab. Teriparatide is reserved for patients with severe osteoporosis and the use of strontium ranelate is declining because of cardiovascular safety concerns.

18.
Acta Radiol ; 56(6): 714-9, 2015 Jun.
Artigo em Inglês | MEDLINE | ID: mdl-24919465

RESUMO

Subchondral insufficiency fracture of the knee (SIFK) is a potentially devastating disorder that may progress rapidly to osteoarthritis with articular surface collapse. It should be suspected in the appropriate clinical setting, as in early stages it is usually indistinct on initial plain radiographs and magnetic resonance imaging is required for a definitive diagnosis. Outcome of SIFK depends on several factors, including the initial subchondral fracture size, patient BMI, degree of osteopenia, as well as early diagnosis and initial treatment. The purpose of this paper is to review the clinical presentation, pathophysiology, image findings, complications and outcome of SIFK.


Assuntos
Cartilagem Articular/lesões , Fraturas de Estresse/diagnóstico , Traumatismos do Joelho/diagnóstico , Imageamento por Ressonância Magnética , Humanos
19.
Molecules ; 20(9): 17362-77, 2015 Sep 18.
Artigo em Inglês | MEDLINE | ID: mdl-26393566

RESUMO

Two solution-processable small organic molecules, (E)-6,6'-bis(4-(diphenylamino)phenyl)-1,1'-bis(2-ethylhexyl)-(3,3'-biindolinylidene)-2,2'-dione (coded as S10) and (E)-6,6'-di(9H-carbazol-9-yl)-1,1'-bis(2-ethylhexyl)-(3,3'-biindolinylidene)-2,2'-dione (coded as S11) were successfully designed, synthesized and fully characterized. S10 and S11 are based on a donor-acceptor-donor structural motif and contain a common electron accepting moiety, isoindigo, along with different electron donating functionalities, triphenylamine and carbazole, respectively. Ultraviolet-visible absorption spectra revealed that the use of triphenylamine donor functionality resulted in an enhanced intramolecular charge transfer transition and reduction of optical band gap, when compared with its carbazole analogue. Both of these materials were designed to be donor semiconducting components, exerted excellent solubility in common organic solvents, showed excellent thermal stability, and their promising optoelectronic properties encouraged us to scrutinize charge-carrier mobilities using solution-processable organic field effect transistors. Hole mobilities of the order of 2.2 × 10(-4) cm²/Vs and 7.8 × 10(-3) cm²/Vs were measured using S10 and S11 as active materials, respectively.


Assuntos
Indóis/química , Indóis/síntese química , Aminas/química , Carbazóis/química , Estrutura Molecular , Semicondutores
20.
Molecules ; 20(12): 21787-801, 2015 Dec 04.
Artigo em Inglês | MEDLINE | ID: mdl-26690103

RESUMO

Through the incorporation of a thiophene functionality, a novel solution-processable small organic chromophore was designed, synthesized and characterized for application in bulk-heterojunction solar cells. The new chromophore, (2Z,2'Z)-2,2'-(1,4-phenylene)bis(3-(5-(4-(diphenylamino)phenyl)thiophen-2-yl)acrylonitrile) (coded as AS2), was based on a donor-acceptor-donor (D-A-D) module where a simple triphenylamine unit served as an electron donor, 1,4-phenylenediacetonitrile as an electron acceptor, and a thiophene ring as the π-bridge embedded between the donor and acceptor functionalities. AS2 was isolated as brick-red, needle-shaped crystals, and was fully characterized by ¹H- and (13)C-NMR, IR, mass spectrometry and single crystal X-ray diffraction. The optoelectronic and photovoltaic properties of AS2 were compared with those of a structural analogue, (2Z,2'Z)-2,2'-(1,4-phenylene)bis(3-(4-(diphenylamino)phenyl)-acrylonitrile) (AS1). Benefiting from the covalent thiophene bridges, compared to AS1 thin solid film, the AS2 film showed: (1) an enhancement of light-harvesting ability by 20%; (2) an increase in wavelength of the longest wavelength absorption maximum (497 nm vs. 470 nm) and (3) a narrower optical band-gap (1.93 eV vs. 2.17 eV). Studies on the photovoltaic properties revealed that the best AS2-[6,6]-phenyl-C61-butyric acid methyl ester (PC61BM)-based device showed an impressive enhanced power conversion efficiency of 4.10%, an approx. 3-fold increase with respect to the efficiency of the best AS1-based device (1.23%). These results clearly indicated that embodiment of thiophene functionality extended the molecular conjugation, thus enhancing the light-harvesting ability and short-circuit current density, while further improving the bulk-heterojunction device performance. To our knowledge, AS2 is the first example in the literature where a thiophene unit has been used in conjunction with a 1,4-phenylenediacetonitrile accepting functionality to extend the π-conjugation in a given D-A-D motif for bulk-heterojunction solar cell applications.


Assuntos
Corantes/química , Tiofenos/química , Cristalografia por Raios X , Eletroquímica , Processos Fotoquímicos , Energia Solar , Soluções
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