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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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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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Design, synthesis and structural optimization of two click modified butterfly molecules: Aggregation induced ratiometric fluorescence change and ICT associated hydrogen bonding effect in solvatochromic analysis
摘要： Two click modi?ed butter?y molecules are designed and synthesized having presence and absence of the aggregative moiety to differ between aggregation induced ratiometric emission changes via excimer formation and ICT associated hydrogen bonding effect. These two distinct phenomena can be successfully employed in solvatochromic analysis. This is also supported by the theoretical study through the structural variation of the two butter?y molecules.
关键词： Hydrogen bonding,Butter?y molecules,Ratiometric,AIE,Solvatochromic
更新于2025-09-23 15:22:29
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Medium viscosity effect on fluorescent properties of Sn(IV)-tetra(4-sulfonatophenyl)porphyrin complexes in buffer solutions
摘要： Supramolecular triads consisting of hydrophilic Sn(IV)-tetra(4-sulfophenyl)-porphyrin and two axial guests such as propylphenol, tyrosine, and 2-(2-hydroxyphenyl)-benzoxazole were synthesized. The structures of synthesized complexes were identified by experimental spectroscopic and quantum-chemical simulation methods, and their fluorescent properties were studied in various viscosity media (mixed phosphate buffer-glycerin solvents of different composition). The effect of axial ligand structure on the fluorescent properties of these triads (due to the hydrogen bonding or π-π stacking between the components of ?host-guest? systems) is discussed. The potential use of synthesized complexes as environmental probes of local viscosity is proposed.
关键词： synthesis,ROESY,fluorescent properties,hydrogen bonding,DOSY,2D NMR,DFT,viscosity,Sn(IV)-porphyrins
更新于2025-09-23 15:22:29
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Self-Assembly of a Carboxyl-Functionalized BODIPY Dye via Hydrogen Bonding
摘要： We report the synthesis, characterization, and self-assembly behavior of a 4,4-Difluoro-4-bora-3a,4a-diaza-s-indacene (BODIPY) dye functionalized at the meso-position with a butyric acid group. Various spectroscopic investigations (UV-Vis, emission, and Fourier-transform infrared spectroscopy (FTIR) studies) supported by X-ray analysis revealed the formation of self-assembled structures in the solid state with translationally stacked BODIPY units driven by hydrogen bonding between the carboxyl groups.
关键词： hydrogen bonding,Self-Assembly,weak non-covalent interactions,BODIPY dyes
更新于2025-09-23 15:21:21
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Investigation of the Physical Properties of Plasma Enhanced Atomic Layer Deposited Silicon Nitride as Etch Stopper
摘要： Correlations between physical properties linking film quality with wet etch rate (WER), one of the leading figures of merit, in plasma-enhanced atomic layer deposition (PEALD) grown silicon nitride (SiNx) films remain largely unresearched. Achieving a low WER of a SiNx film is especially significant in its use as an etch stopper for technology beyond 7 nm node semiconductor processing. Herein, we explore the correlation between the hydrogen concentration, hydrogen bonding states, bulk film density, residual impurity concentration, and the WERs of PEALD SiNx using Fourier transform infrared spectrometry, X-ray reflectivity, and spectroscopic ellipsometry, etc. PEALD SiNx films for this study were deposited using hexachlorodisilane and hollow cathode plasma source under a range of process temperatures (270 °C – 360 °C) and plasma gas compositions (N2/NH3 or Ar/NH3) to understand the influence of hydrogen concentration, hydrogen bonding states, bulk film density, and residual impurity concentration on the WER. Varying hydrogen concentration and differences in the hydrogen bonding states resulted in different bulk film densities, and accordingly, a variation in WER. We observe a linear relationship between hydrogen bonding concentration and WER as well as a reciprocal relationship between bulk film density and WER. Analogous to the PECVD SiNx processes, a reduction in hydrogen bonding concentration arises from either (1) thermal activation or (2) plasma excited species. However, unlike the case with silane (SiH4)-based PECVD SiNx, PEALD SiNx WERs are affected by residual impurities of Si precursors (i.e., chlorine impurity). Thus, possible wet etching mechanisms in HF in which the WER is affected by hydrogen bonding states or residual impurities are proposed. The shifts of amine basicity in SiNx due to different hydrogen bonding states and the changes in Si electrophilicity due to Cl impurity content are suggested as the main mechanisms that influence WER in the PEALD processes.
关键词： plasma-enhanced ALD (PEALD),bulk film density,hexachlorodisilane (HCDS),wet etch rate (WER),silicon nitride,hydrogen/chlorine content,atomic layer deposition (ALD),hydrogen bonding state
更新于2025-09-23 15:21:01
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Synthesis of “lotus root”-like mesoporous titanium dioxide and its effects on UV response to aconitine release
摘要： Mesoporous titanium dioxide with a “lotus root”-like structure was synthesized for the first time using an improved template-free method. The structure has a BET (Brunauer Emmett Teller) surface area of 688.11 m2/g, a pore volume of 0.743 cm3/g, and a pore size of 3.59 nm. Aconitine, a botanical insecticide, could be loaded onto the mesoporous titanium dioxide via simply soaking the structure and had a maximum loading of 17.6 %. UV spectroscopy was utilized to explore the drug release behaviors, and the results showed that aconitine-loaded mesoporous titanium dioxide particles UV irradiated could successfully release aconitine with a release rate of 46.24%, which was significantly higher than the samples lacking UV irradiation (36.80%). Meanwhile, the release rate of aconitine (48.94 %) for pH 5.5 was significantly higher than that for pH 7.0 (42.09 %). The results of microcalorimetry revealed that both the enthalpy change (?H) and entropy change (?S) were negative (?H < 0, ?S < 0) for the whole process of aconitine loading onto the “lotus root”-like mesoporous titanium dioxide support. Hydrogen bonding was the driving force for drug loading, and this was also verified using Monte Carlo simulations. These results show that the “lotus root”-like mesoporous titanium dioxide material has some potential applications such as the storage and use of plant pesticides.
关键词： “Lotus root”-like mesoporous titanium dioxide,Monte Carlo simulations,hydrogen bonding,UV-responsed drug release
更新于2025-09-23 15:21:01
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Impact of electronically excited state hydrogen bonding on luminescent covalent organic framework: a TD-DFT investigation
摘要： The investigation of intermolecular hydrogen bonding between the luminescent polypyrene covalent organic framework and formaldehyde (PPy-COF-HCHO) was carried out with the density functional theory and time-dependent density functional theory. The strengthening of the photoexcited hydrogen bond C = O—H–C was verified via geometric structures, electronic transition energies, binding energies, UV-Vis and infrared spectra comparison in both ground state and excited state of the PPy-COF’s truncated representative fragment. From the frontier molecular orbitals examination, natural population analysis, and plotted electron density difference map demonstrated that the strengthened hydrogen bond facilitated the rearrangement of electron density between H-donor and H-acceptor moieties which should account for charge transfer and ultimate fluorescence quenching. Interestingly, the energy gap between excited state and triplet state of the hydrogen-bonded complex showed the possibility of the intersystem crossing. The MOMAP programme further confirmed the quenching process because there was a lower fluorescent rate constant for the donor–acceptor PPy-COF-HCHO complex compared to free PPy-COF fragment. Results above significantly highlighted the high sensitivity of the PPy-COF towards organic analyte, i.e. the formaldehyde and can be employed as a sensor.
关键词： luminescence,TD-DFT,MOMAP,hydrogen bonding
更新于2025-09-23 15:21:01