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Investigations on the quantum chemical studies and physico-chemical properties of an opto-electronic material 1-Allyl-2-Aminopyridine-1-ium bromide
摘要： In the present work, the dual approach of quantum chemical studies and experimental characterizations of the title compound 1-Allyl-2-Aminopyridine-1-ium bromide (1A2APB) were carried out for the first time. The molecular geometry of 1A2APB was optimized by density functional theory (DFT) using B3LYP/6-311++G (d,p) basis set. The optimized geometric structural parameters were compared with the experimental findings and discussed. The dipole moment (μ) and first hyperpolarizability (β) were calculated to predict the NLO behavior. The frontier molecular orbital (FMO), molecular electrostatic potential (MESP), Mulliken atomic charge and thermodynamic properties were investigated to get a better insight of the molecular properties. Stability of the compound arising from hyper-conjugative interactions, intra-molecule re-hybridization and charge delocalization within the molecule were analyzed using NBO analysis. Further, 1A2APB was synthesized and good quality single crystals were grown by slow evaporation technique. Studies such as microanalysis and powder XRD were performed to ascertain material composition and phase respectively. The various characteristic functional groups were identified through FT-IR spectroscopic analyses. The NLO efficiency was measured to be about greater than 5 times that of standard KDP. Thermal behaviors were explored by the simultaneous TG/DTA-DSC thermograms. The UV–Vis–NIR spectral data and fluorescence spectrum were recorded to explore the optical transmission and emission properties respectively. The dielectric properties were evaluated as a function of frequency at various temperatures. The photoconducting nature was analyzed through photoconductivity measurement. The Vicker’s microhardness test was performed at room temperature from which the mechanical stability was analyzed through the classical Meyer’s relation.
关键词： Photoconductivity,Powder XRD analysis,DFT calculations,Organic materials,Non-linear optics,Crystal growth
更新于2025-09-23 15:23:52
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Metal-Organic Frameworks as Hosts for Fluorinated Azobenzenes: A Path Towards Quantitative Photoswitching with Visible Light
摘要： Fifteen new photochromic hybrid materials were synthesized by gas phase loading of fluorinated azobenzenes, namely ortho-tetrafluoroazobenzene (tF-AZB), 4H,4H'-octafluoroazobenzene (oF-AZB), and perfluoroazobenzene (pF-AZB), into the pores of the well-known metal-organic frameworks MOF-5, MIL-53(Al), MIL-53(Ga), MIL-68(Ga), and MIL-68(In). Their composition was analysed by elemental (CHNS) and DSC/TGA analysis. For pF-AZB0.34@MIL-53(Al) a structural model based on high-resolution synchrotron powder diffraction data was developed and the host-guest and guest-guest interactions were elucidated from this model. These interactions of O-H…F and π…π type were confirmed by significant shifts of the O-H frequencies in loaded and unloaded MOFs of the MIL-53 and MIL-68 series. Most remarkably, all of the synthesized F-AZB@MOF systems can be switched with visible light and some of them show almost quantitative (> 95 %) photo-isomerization between its E and Z forms with no significant fatigue after repeated switching cycles.
关键词： azobenzene,fluorinated derivatives,solid state switching,metal-organic frameworks,photochromism
更新于2025-09-23 15:23:52
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Super photo-base initiated organic-inorganic hybrid coatings by plural-cure mechanisms
摘要： Free-radical polymerization forms the core chemistry of a majority of commercial UV-curable coating system today. Rapid curing at ambient temperature using stable, single component coating systems form the key value proposition that such coating systems offer. However, owing to their limitations such as oxygen inhibition, volume shrinkage, toxicity profiles of reactive diluents (RD), and the limited chemistry available, efforts are being made to counter these challenges by innovating and exploring new systems that have the potential to replace the existing chemistries. Anionic polymerization is one such promising area that has the potential to introduce a wide variety of chemistries in the field of UV-curable coatings. A significant stride in this field has been the innovation of photo-labile bases in the UV industry and the diverse chemistries that these bases have brought to fore. The primary focus of the present study is use of a super photo-base generator (PBG) in catalyzing concomitant but independent reactions to develop organic-inorganic hybrid (OIH) coating networks by leveraging plural-cure chemistry. The super PBG has been used to initiate both Michael-addition (MA) reaction and sol-gel reaction concurrently, upon exposure to the UV source. Coatings have been formulated using uniquely designed acrylate functional oligomers (MA-acceptor), acetoacetate functional reactive diluents (MA-donors) and organo-silanes (sol-gel precursors), besides super PBG. The study highlights many technical and environmental benefits of these OIH coatings with potential for applications in advanced coatings and additive manufacturing.
关键词： Reactive diluent,Super photo-base,Organic-inorganic hybrid,Michael-Addition
更新于2025-09-23 15:23:52
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Synthesis, Structure, and Photoluminescence Properties of a Metal-Organic Framework with Hexagonal Channels: Selective Turn-On Sensing for Mg <sup>2+</sup> Ion
摘要： A three-dimensional Cd2+ framework (1) with wide one-dimensional hexagonal channels was prepared based on a tripodal tricarboxylate ligand possessing nitrogen donor atoms. The Cd atoms form a chain structure bridged by carboxylates and aqua ligands. Upon Mg2+ ion capture, the fluorescence emission of this porous material was 5.2 times greater than its Mg2+-free fluorescence. To the best of our knowledge, such enhancement has not been previously reported for metal–organic framework sensory systems. The sensing performance of 1 is reversible over repeated cycles of Mg2+ inclusion and release, revealing the reusability of this material. In the presence of other tested metal ions, Mg2+ ions were selectively detected owing to the operation of this “turn-on” mechanism. Thus, this platform is a promising sensor material for selective Mg2+ ion recognition.
关键词： Sensors,Luminescence,Metal-organic frameworks
更新于2025-09-23 15:23:52
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Engineering organic electrochemical transistor (OECT) to be sensitive cell-based biosensor through tuning of channel area
摘要： The barrier integrity of epithelial tissue is crucial to many physiological functions in multicellular organisms. Hence, several scientific techniques, such as epithelial voltohmmeter (EVOM) and electric cell-substrate impedance sensing (ECIS), were developed to assess barrier function for in vitro assays. Organic electrochemical transistor (OECT), in particular, outperforms many biosensors because of its multiple advantages such as high transconductance, mixed ionic-electronic conductivity and high biocompatibility. Despite its extensive application in cell impedance sensing, little was reported on how its geometrical dimensions would affect the device performance and quality of cell-based measurement. In this work, OECTs in different dimensions were fabricated and characterized. Specifically investigated were their time and frequency responses towards the presence of epithelial cells (i.e. tightly packed colorectal adenocarcinoma cell line caco-2 and a novel leaky nasopharyngeal carcinoma cell line NPC43). Results show that the sensitivity of cell-based measurement is closely related to the impedance of the whole cell-OECT system. The performance of cell-based sensor would be affected by the tightness of target cell and can be tuned by controlling the active area of OECT.
关键词： Conducting polymer,Frequency response,Biosensor,Impedance spectroscopy,Transepithelial electrical resistance,Organic electrochemical transistor
更新于2025-09-23 15:23:52
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Structure, growth and characterization of a new naphthalene family crystal for fluorescence and third order nonlinear optical applications
摘要： In the present work we have investigated the fluorescence and nonlinear optical property of a new naphthalene family crystal, Decyl 6-(decyloxy)naphthalene-2-carboxylate (D6DN2C). This crystal was grown for the first time by slow evaporation solution technique (SEST). Single crystal X-ray diffraction analysis reveals that D6DN2C belongs to triclinic crystal system with centrosymmetric space group of Pī. The determined lattice parameters are a = 8.669(3) ?, b = 9.495(3) ?, c = 19.757(6) ?, α =82.697(1)°, β =77.726(1)°, γ = 65.465(1)°and volume = 1444.17(8)?3. Functional groups present in D6DN2C were identified by FT-IR studies. Transparency of the title crystal in UV–Visible region was analyzed and the optical band gap energy was found to be 3.51eV. Fluorescence spectra were recorded for the excitation wavelength of 300 nm. The negative third order nonlinear optical parameters like refractive index (n2), absorption coefficient (β) and susceptibility (χ(3)) were estimated by Z-scan studies.
关键词： Crystal structure,Characterization,Growth from solutions,Nonlinear optic materials,Organic compounds
更新于2025-09-23 15:23:52
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A fluorescent Eu(III) MOF for highly selective and sensitive sensing of picric acid
摘要： A metal-organic framework [Eu3L3(CH3COO)2(H2O)2(μ3-OH)]?3DMF, (EuL, H2L=9H-carbazole-2,7-dicarboxylic acid, DMF=N,N-dimethylformamide) has been synthesized under solvothermal conditions and structurally characterized. In EuL, Eu6O8 clusters are four-bridged by carboxylates to form parallel-aligned Eu–O–C chains, which are further linked by the carbazole moieties of L2? ligands to form the three-dimensional framework with rhombic channels. The EuL material with characteristic emission of Eu3+ ion exhibits significant luminescence quenching response for picric acid (PA) and the linear Stern-Volmer plot was observed in the concentration range of 0.05–0.15 mM with Ksv of 98074 M?1. As far as we know, this Ksv is among the highest values for COFs and MOFs in detection of PA. The excellent anti-interference ability and repeatability were also verified by experiments. Lastly, we investigated the luminescence quenching mechanism in the EuL sensing system.
关键词： europium,picric acid,sensor,metal-organic frameworks
更新于2025-09-23 15:23:52
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Water-Stable Metal–Organic Frameworks with Selective Sensing on Fe <sup>3+</sup> and Nitroaromatic Explosives, and Stimuli-Responsive Luminescence on Lanthanide Encapsulation
摘要： Three water-stable luminescent MOFs [Zn4(bptc)2(NMP)3(DMF)(H2O)2]n (1-a), [Cd4(bptc)2(NMP)3(DMF)2(H2O)1]n (1-b), and {[Zn2(bptc)(DMA)(H2O)2]·(DMA)2·H2O}n (2), possessing similar chemical components (M2:L1:Sol3) and topology structures, were synthesized by solvents control. Their excellent sensing on iron(III) cation and nitroaromatic explosives (NACs) with great selectivity, sensitivity and a high Ksv (4.54 × 10^4 for 1-b on PNP) were observed by quenching effects. Furthermore, Zn-MOFs exhibit interesting stimuli-responsive luminescence enhancement after the encapsulation of a series of IIIB cations stimulated different luminescent emitting and intensity enhancement through host–guest processes of the pores in MOFs, especially for two distinct responses of Zn-MOF on a Tb3+ cation.
关键词： stimuli-responsive,nitroaromatic explosives,luminescent,water-stable,lanthanide encapsulation,iron(III),metal-organic frameworks,sensing
更新于2025-09-23 15:23:52
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Simultaneous Singlet–Singlet and Triplet–Singlet F?rster Resonance Energy Transfer from a Single Donor Material
摘要： For almost 70 years, F?rster resonance energy transfer (FRET) has been investigated, implemented into nowadays experimental nanoscience techniques, and considered in a manifold of optics, photonics and optoelectronics applications. Here, we demonstrate for the first time simultaneous and efficient energy transfer from both donating singlet and triplet states of a single photoluminescent molecular species. Using a biluminescent donor that can emit with high yield from both excited states at room temperature allows to apply the FRET framework to such a bimodal system. It serves as an exclusive model system where the spatial origin of energy transfer is exactly the same for both donating spin states involved. Of paramount significance are the facts that both transfers can easily be observed by eye and that F?rster theory is successfully applied to state lifetimes spanning over eight orders of magnitude.
关键词： organic light-emitting diodes,energy transfer,biluminescence,dual state FRET
更新于2025-09-23 15:23:52
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Q-graphene-scaffolded covalent organic frameworks as fluorescent probes and sorbents for the fluorimetry and removal of copper ions
摘要： Metal-free fluorescent covalent organic frameworks (COFs) were synthesized initially with Q-Graphene (QG) scaffolds by the one-step covalent reactions of melamine-aldehyde and phenol-aldehyde poly-condensations using paraformaldehyde. It was discovered that onion-like hollow QG, which consists of multi-layer graphene and different carbon allotropes having a high proportion of folded edges and surface defects, could endow the scaffolded COFs with enhanced green fluorescence and environmental stability. Unexpectedly, they could exhibit the powerful absorption for Cu2+ ions resulting in the specific quenching of fluorescence. A fluorimetric strategy with QG-scaffolded COFs was thereby developed to probe Cu2+ ions separately in blood and wastewater with the linear concentration ranges of 0.0010 - 10.0 μM (limit of detection of 0.50 nM) and 0.0032 - 32.0 μM (limit of detection of 2.4 nM), respectively, promising the potential applications for the field-applicable monitoring of Cu2+ ions in the clinical and environmental analysis fields. In addition, the prepared COFs sorbents were employed to absorb Cu2+ ions in wastewater showing high removal efficiency. More importantly, such an one-pot fabrication route with hollow QG scaffolds may be tailorable extensively for the preparation of a variety of metal-free multifunctional COFs with enhanced fluorescence, water solubility, environmental stability, and metal removal capability.
关键词： Q-Graphene Scaffold；Covalent Organic Frameworks；Fluorescent Analysis；Removal Sorbents；Copper Ions
更新于2025-09-23 15:23:52