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Luminescence and anion recognition performance of mononuclear Eu(III) complexes with N- and O- donor pyridine derivatives
摘要： A series of Eu(III) complexes with pyridine-2-carboxamide (PCA), pyridine-2-carboxaldoxime (PCAO), pyridine-2,3-dicarboxylic anhydride (PDCA) or pyridine-2-methanol (PM) as primary ligands and 4,4′-dimethoxy-2,2′-bipyridine (DMBP) as ancillary ligand were synthesized. The interaction between the ligands and complexes were confirmed by FT-IR study. The complexes were abbreviated as [Eu(PCA)3DMBP].Cl3 (C1), [Eu(PCAO)3DMBP].Cl3 (C2), [Eu(PDCA)3DMBP].Cl3 (C3) and [Eu(PM)3DMBP].Cl3 (C4). Optical studies were done by UV–vis spectroscopy and PL spectroscopy. The highest intrinsic luminescent quantum yield (53.42%) and lifetime value (1456 μs) were found for C3. Lowest quantum yield was exhibited by C2. Anion sensing studies of all the complexes were done by UV–vis and PL spectroscopy and it was observed that complex C1 showed remarkable change in optical properties upon addition of F? and HSO4? ions. Thus C1 can be used as optical sensor for F? and HSO4? ions. The FQD for F? and HSO4? ions were found to be 6.55 and 3.58 respectively for C1.
关键词： Sensing performance,Antenna effect,Hydrogen bonding,Optical sensor,Lifetime decay
更新于2025-11-21 11:18:25
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Control of Excited-State Supramolecular Assembly Leading to Halide Photorelease
摘要： Ground- and excited-state control of halide supramolecular assembly was achieved through the preparation of a series of ester- and amide-functionalized ruthenium polypyridyl complexes in CH2Cl2. Hydrogen-bonding amide and alcohol groups on the receptor ligand were found to direct interactions with halide, while halide association with the ethyl ester groups was not observed. The various functional groups on the receptor ligands tuned the ground-state equilibrium constants over 2 orders of magnitude (1 × 10^5 to 1 × 10^7 M^?1), and the fractional contribution of each hydrogen-bond donor to the total equilibrium constant was determined. Pulsed-laser excitation of the complexes resulted in excited-state localization on the ester- or amide-functionalized ligands. In the case where the excited state was oriented toward an associated halide ion (the amide complexes), an 80 ± 10 meV Coulombic repulsion was induced that lowered the excited-state equilibrium constant (K*_eq) and resulted in halide photorelease. The rate constants for excited-state halide release (k*_21) were determined, and the values varied based on the functional groups present in the receptor ligand. Complexes with more hydrogen-bonding donors had smaller rate constants for halide photorelease. In a complex without a specific receptor ligand, the excited-state dipole was not oriented toward the associated halide, and the excited state was therefore found to have a larger equilibrium constant for halide association than the ground state.
关键词： halide supramolecular assembly,excited-state equilibrium,photorelease,hydrogen-bonding,ruthenium polypyridyl complexes
更新于2025-11-19 16:56:35
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Mechanical analysis of the interface bonding state of a TiO2 film/Si substrate
摘要： TiO2 film is prepared on the surface of a natural oxide layer of a monocrystalline silicon substrate via RF magnetron sputtering. HRTEM (High Resolution Transmission Electron Microscope) imaging and EDX spectroscopy are performed on the sample interface, demonstrating that the film sample has a two-layer structure. Combined with XRD, the analysis shows that the upper film is a crystalline TiO2 film with a thickness of approximately 30 nm and that the lower film is a natural amorphous SiO2 oxide film with a thickness of approximately 22 nm. A geometric phase analysis (GPA) and Hooke's law are used to analyse the stress and bonding state at the interfaces between the monocrystalline silicon substrate and the natural oxide layer, between rutile TiO2 and the natural oxide layer, and between anatase TiO2 and the natural oxide layer. It is concluded that the interface bonding state of the monocrystalline silicon/natural oxide layer is good and that the interface bonding state at the interface between rutile and the natural oxide layer is better than that between anatase and the natural oxide layer.
关键词： geometric phase analysis,Hooke's law,natural oxidation,interface bonding states,TiO2
更新于2025-11-14 17:04:02
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[IEEE 2018 7th Electronic System-Integration Technology Conference (ESTC) - Dresden, Germany (2018.9.18-2018.9.21)] 2018 7th Electronic System-Integration Technology Conference (ESTC) - Integration with Light
摘要： This paper reports the use of Laser-induced Forward Transfer (LIFT) technology for printing of multilayer flexible circuitries and the fabrication of micro-bumps for flip-chip bonding of packaged LEDs and bare die microcomponents. Bonding of passive and functional surface mount devices (SMD) on low-temperature polyethylene terephthalate (PET) foils have been demonstrated using two selective bonding techniques. Firstly, using a high intensity near-infrared (NIR) lamp, a bare die NFC chip was bonded on micro-bumps formed with LIFT printed isotropic conductive adhesive (ICA) within less than a minute. Secondly, using a high intensity Xenon lamp, passive components and packaged LEDs were bonded within 5 seconds on micro-bumps formed with conventional Sn–Ag–Cu (SAC) lead-free alloys. In the both cases, due to selective light absorption, a limited temperature increase was observed in the PET substrates allowing successful bonding of components onto the delicate polyethylene foil substrates using conventional interconnect materials.
关键词： LIFT,low temperature bonding,NIR curing,conductive adhesive,lead-free SAC solder,photonic soldering,flip-chip bonding,laser printing
更新于2025-09-23 15:23:52
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B-Doping-Enhanced Stability of Phosphorene/Graphene Heterostructures
摘要： Two-dimensional material heterostructures show large surface area and unusual electronic properties, being used in nanoelectronic devices, energy storage devices, and sensors. Doping can improve stability of the heterostructures. Structural and electronic properties of B–doped phosphorene/graphene heterostructures are studied using ?rst-principles calculations. B doping in phosphorene enhances the interlayer charge transfer from phosphorene to graphene. Importantly, B doping creates strong chemical bonding at the interface, which improves stability of phosphorene/graphene heterostructures. The band gap is opened up to 0.53 eV by B doping.
关键词： heterostructure,DFT calculations,graphene,phosphorene,chemical bonding
更新于2025-09-23 15:23:52
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Hard X-ray photoelectron spectroscopy investigation of annealing effects on buried oxide in GaAs/Si junctions by surface-activated bonding
摘要： Hard X-ray photoelectron spectroscopy measurements are performed on ≈10-nm-thick GaAs film/Si substrate junctions fabricated by the surface activated bonding and selective wet etching. The chemical shifts of Ga-O and As-O signals in Ga 2p3/2 and As 2p3/2 core spectra indicate that oxides are formed in a part of GaAs films neighboring GaAs/Si interfaces due to the surface activation process. Analyses of Ga-O and As-O signals show that the thickness of such buried oxides is decreased due to a post-bonding annealing at temperatures up to 400 °C. This means that the electrical properties of bonding interfaces, which are in the meta-stable states, are improved by the annealing. The thickness of oxides is different from that of amorphous-like transition layers at the GaAs/Si interfaces observed by transmission electron microscopy.
关键词： Buried interface,Surface activated bonding,GaAs/Si,HAXPES
更新于2025-09-23 15:23:52
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Synthesis and fluorescence studies of selected N-aryl-2-aminoquinolines: Effect of hydrogen bonding, substituents and ESIPT on their fluorescence quantum yields
摘要： N-aryl-2-aminoquinolines have been widely synthesised and used in biological applications. However, their luminescence properties have not been studied in detail. Herein a series of N-aryl-2-aminoquinolines was synthesised from substitution reaction between 2-chloroquinoline and anilines with different substituent groups gave sufficient yield from 72–90%. The fluorescence behaviour was investigated in toluene, ethyl acetate and ethanol. The result shows that fluorescence quantum yield of N-aryl-2-aminoquinolines was the highest in toluene, followed by in ethyl acetate and the lowest in ethanol. Quenched emission observed in ethanol is caused by site-specific fluorophore-solvent hydrogen bonding interactions, inducing deactivation of the quinolinyl ring system. The bell-shaped Hammett plot of various substituted compounds suggested that both strong electron donating and electron withdrawing groups caused significant quenching in the fluorescence quantum yields. Therefore, most types of substituent groups on the phenyl moiety, hydrogen bonding between the fluorophore and solvent, and excited-state intramolecular proton transfer (ESIPT) were found as crucial contributors to fluorescence quenching of N-aryl-2-aminoquinolines.
关键词： Substituent effects,ESIPT,Hydrogen bonding,N-aryl-2-aminoquinolines,Fluorescence quenching
更新于2025-09-23 15:23:52
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Ru(II) and Ir(III) complexes containing ADA and DAD triple hydrogen bonding motifs: Potential tectons for the assembly of functional materials.
摘要： The synthesis and characterisation of series of [Ru(II)(bpy)2L] and [Ir(ppy)2L] complexes containing ligands L with the potential to engage in triple hydrogen bonding interactions is described. L1 and L2 comprise pyridyl triazole chelating units with pendant diaminotriazine units, capable of donor-acceptor-donor (DAD) hydrogen bonding, while L3 and L4 contain ADA hydrogen bonding units proximal to N^N and N^O cleating sites, respectively. X-ray crystallography shows the L1 and L2 containing Ru(II) complexes to assemble via R22(8) hydrogen bonding dimers, while [Ru(II)(bpy)2L4] assembles via extended hydrogen bonding motifs to form one dimensional chains. By contrast, the expected hydrogen bonding patterns are not observed for the Ru(II) and Ir(III) complexes of L3. Spectroscopic studies show that the absorption spectra of the complexes result from combinations of MLCT and LLCT transitions. The L1 and L2 complexes of Ir(III) and Ru(II) complexes are emissive in the solid state and it seems likely that hydrogen bonding to complementary species may facilitate tuning of their 3ILCT emission. Low frequency Raman spectra provide further evidence for ordered interactions in the solid state for the L4 complexes, consistent with the results from X-ray crystallography.
关键词： crystal engineering,ruthenium,Hydrogen bonding,iridium,X-ray crystallography
更新于2025-09-23 15:23:52
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Role of solvent H-bonding and polarity on photophysical properties of a benzothiazole-based ratiometric amyloid fibril sensor
摘要： Detailed photophysical properties of 2-[2′-Me,4′-(dimethylamino)-phenyl]benzothiazole (2Me-DABT), a potential ratiometric amyloid fibril sensor, have been investigated in different solvents and solvent mixtures using steady state and time-resolved spectroscopic techniques. Our studies show that emission properties of 2Me-DABT are significantly modulated by polarity of solvent media. Extent of solvatochromism (3585 cm?1) shown by 2Me-DABT is quite large and can be used to monitor micropolarity of different complex media. Further, Stokes’ shift (> 10,000 cm?1) shown by 2Me-DABT in all studied solvents is also much larger than most common molecular probes. It has also been shown that hydrogen bonding with solvent molecules results in large modulation in photophysical properties of 2Me-DABT. The H-bonding with water molecules induces a large change (39°) in the dihedral angle between benzothiazole and aniline moieties resulting large changes in photophysical properties of 2Me-DABT in polar protic solvents. Photophysical properties reported herein are used to explain observed amyloid sensing behaviour of 2Me-DABT. Detailed quantum chemical calculations are performed to support the experimental results.
关键词： Amyloid sensor,H-bonding,Photophysics,Time-resolved spectroscopy,Fluorescence
更新于2025-09-23 15:23:52
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Photoresponsive Halogen-Bonded Liquid Crystals: The Role of Aromatic Fluorine Substitution
摘要： A new strategy for controlling the liquid crystalline and photophysical properties of supramolecular mesogens assembled via halogen bonding is reported. Changing the degree of fluorination at the halogen-bond donor of the supramolecular liquid crystal allows for the fine-tuning of the halogen bond strength and thereby provides control over the temperature range of the mesophase. At least three fluorine atoms have to be present to ensure efficient polarization of the halogen-bond donor and the formation of a mesophase. In addition, it was found that stilbazole acceptors are superior to their azopyridine counterparts in promoting stable liquid crystalline phases. The halogen-bond-driven supramolecular liquid crystals between fluorinated azobenzenes and stilbazole/azopyridine acceptors show a rich variety of photoinduced processes driven by azobenzene photoisomerization, dictated not only by the photochemical properties of the molecular components but also by the difference between the operation temperature and the clearing point.
关键词： photoresponsive materials,fluorination,supramolecular chemistry,azobenzenes,halogen bonding,liquid crystals
更新于2025-09-23 15:23:52