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Hydrogen Bonds and Molecular Orientations of Supramolecular Structure between Barbituric Acid and Melamine Derivative at the Air/Water Interface Revealed by Heterodyne-Detected Vibrational Sum Frequency Generation Spectroscopy
摘要： We studied the supramolecular structure between barbituric acid (pyrimidine-2,4,6(1H,3H,5H)-trione, BA) and an amphiphilic melamine derivative at the air/water interface by heterodyne-detected vibrational sum frequency generation (HD-VSFG) spectroscopy. HD-VSFG measurements in situ showed a positive broad band from 2300 to 2950 cm?1. By comparing the experimental results with ab initio molecular dynamics (AIMD) simulations, we assigned the broad band to the NH stretching modes of BA strongly hydrogen-bonded to the melamine derivative. In addition, we report in situ HD-VSFG spectra of the interfacial supramolecular structure in the CO stretching region. Two CO stretching bands were identified. On the basis of the signs of the C=O bands, we uniquely determined the orientation of BA. The strong hydrogen bonds and the molecular orientations are direct evidence for the supramolecular structure based on complementary hydrogen bonds at the air/water interface.
关键词： Supramolecular Structure,Molecular Orientations,Barbituric Acid,Melamine Derivative,Hydrogen Bonds,Air/Water Interface,Heterodyne-Detected Vibrational Sum Frequency Generation Spectroscopy
更新于2025-09-19 17:13:59
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Synthesis of BiOCl: Eu3+ Microarchitectures and their WLED’s, Fingerprint Detection and Anticounterfeiting Applications
摘要： BiOCl: Eu3+(1-9mol %) microarchitectures were synthesized by the solution combustion method by employing Barbituric acid as fuel. The crystal structure, morphologies and luminescence properties of Eu3+ doped BiOCl have been systematically investigated by powder X-ray diffraction (PXRD) and scanning electron microscopy (SEM) and spectroscopy respectively. The prime objective of the current effort was first to fabricate highly luminescent nanophosphor for revelation of latent fingerprints, lips prints including infiltrating and non-filtrating surfaces and also to develop luminescent ink for anticounterfeiting applications. Presently the fingerprints developed by using conventional powders have several disadvantages including low sensitivity, high background hindrance, complicated procedure and high toxicity. To encounter this challenge, we explored the optimized BiOCl:Eu3+(3mol %) nanophosphor for detection of latent fingerprints and luminescent anti-counterfeiting ink. The morphology of the phosphor was tuned by adjusting the concentration of fuel. Photoluminescence studies of BiOCl:Eu3+(1-9mol %) exhibited the peaks 5D0 → 7FJ (J = 0, 1, 2, 3, 4) transitions. The CIE and CCT characteristics specify that the synthesized nanophosphor might be immensely show potential red factor for promising applications in WLED’s. The BiOCl: Eu3+ (1-9 mol %) nanopowder also showed clear ridge patterns of level I and level II and further showed sharp image of label when observed in the UV light. The results indicated that the present phosphor could be used in both forensic as well as in anti counterfeiting applications.
关键词： Barbituric acid,BiOCl,morphology,luminescence,photoluminescence,nanophosphor,Eu3+
更新于2025-09-12 10:27:22
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Non-Fullerene Small Molecule Acceptors Containing Barbituric Acid End Groups for Use in High-performance OPVs
摘要： We synthesized two new bithiophene-based small molecules, TT-BBAR, and TT-OBAR, having butyl- and octyl-substituted barbituric acid (BAR) groups, respectively, via a well-known synthetic method, the Knoevenagel condensation, in high yield. These small molecules displayed solubilities and thermal stabilities sufficient for the fabricating organic photovoltaic cells (OPVs) and were designed to have relatively low molecular orbital energy levels and act as non-fullerene acceptors (NFAs) for use in OPVs upon introduction of electron-withdrawing BAR groups at both ends. For example, the LUMO and HOMO energy levels of TT-OBAR were ?3.79 and of ?5.84 eV, respectively, clearly lower than those of a polymer donor, PTB7-Th. Importantly, the small molecules featured an energy offset with PTB7-Th sufficient for achieving exciton dissociation. The optical and electrochemical properties of TT-BBAR and TT-OBAR did not depend on the alkyl chain length. Finally, OPV devices were fabricated in an inverted structure using a solvent process. The power conversion efficiency of TT-OBAR (1.34%) was found to be slightly higher than that of TT-BBAR (1.16%). The better performance and higher short-circuit current value of TT-OBAR could be explained based on a morphological AFM study, in which TT-OBAR displayed a more homogeneous morphology with a root-mean-square value of 1.18 nm compared to the morphology of TT-BBAR (11.7 nm) induced by increased alkyl chain length.
关键词： Barbituric acid,Organic photovoltaics,Organic photovoltaic cell,Non-fullerene acceptor
更新于2025-09-10 09:29:36
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Far‐Red/Near‐Infrared Emissive (1,3‐Dimethyl)barbituric Acid‐Based AIEgens for High‐Contrast Detection of Metastatic Tumors in Lung
摘要： Despite of the enthusiastic research in aggregation-induced emission luminogens (AIEgens) in recent years, the ones that can be smoothly used for sophisticated biomedical applications such as in vivo bioimaging of pulmonary metastatic tumors during surgery are still limited. Herein, we report the design and synthesis of a new series of fluorescent AIEgens that consist of methoxy-substituted tetraphenylethene (TPE) as the electron-donating moiety, (1,3-dimethyl)barbituric acid as the electron-withdrawing moiety, and different π-bridge units. As compared to benzene or 3,4-ethylenedioxythiophene, using thiophene as the π-conjugation unit between the donor and acceptor results in relatively higher absolute fluorescence quantum yield (14.5%) in water when formulating the corresponding AIEgens into nanoparticles (AIE dots) with amphiphilic co-polymer as the doping matrix. The highly FR/NIR emissive thiophene-based AIE dots are demonstrated to be potent for intraoperative detection of pulmonary metastatic tumors particularly the micro-sized ones with excellent signal-to-background ratio.
关键词： barbituric acid,AIE dot,fluorescence imaging,image-guided cancer surgery,aggregation-induced emission luminogen
更新于2025-09-04 15:30:14