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MCM-SO3H catalyzed synthesis of environment-sensitive fluorophores incorporating pyrene moiety: Optimization, fluorescence emission and theoretical studies
摘要： Six new highly fluorescent 5-(aryl)-1-phenyl-3-(pyren-1yl)-2-pyrazolines were synthesized by reaction of various (E)-3-aryl-1-(pyren-1-yl)prop-2-en-1-ones with phenyl hydrazine in the presence of sulfonated mesoporous silica (MCM-SO3H) as efficient and eco-friendly acidic catalyst. The chemical structures of all synthesized compounds were illustrated on the basis of spectral data (IR, 1H NMR and 13C NMR). This was followed by photophysical properties-based absorption and emission studies of the target compounds in solutions of different solvent polarities. The microenvironment-sensitive fluorescent pyrazolines labeled with pyrene exhibited valuable fluorescence properties with emission in the range of 600–700 nm with a marked response to change in the environmental polarities. A significant and pronounced red shift was observed in the emission spectrum of 5-(aryl)-1-phenyl-3-(pyren-1yl)-2-pyrazolines Δλ ～ 50 nm compared to the absorption spectrum Δλ ～ 10 nm upon increasing the solvent polarity. This indicated the presence of higher dipole moment in the excited state than in the ground state and the transition involved are π-π* transition through the charge transfer phenomena. The fundamental understanding of solvatochromic properties were analyzed through Lippert-Mataga and Reichardts correlations in order to estimate the change in dipole moments (Δμ) which suggested the emissive state of designed fluorescent 2-pyrazoline derivatives is of strong ICT character.
关键词： Pyrene,Solvatochromic properties,Eco-friendly,2-Pyrazolines,Fluorophores,MCM-SO3H
更新于2025-09-10 09:29:36
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Probing of G-Quadruplex Structures via Ligand-Sensitized Photochemical Reactions in BrU-Substituted DNA
摘要： We studied photochemical reactions of BrU-substituted G-quadruplex (G4) DNA substrates with two pyrene-substituted polyazamacrocyclic ligands, M-1PY and M-2PY. Both ligands bind to and stabilize G4-DNA structures without altering their folding topology, as demonstrated by FRET-melting experiments, fluorimetric titrations and CD spectroscopy. Notably, the bis-pyrene derivative (M-2PY) behaves as a significantly more affine and selective G4 ligand, compared with its mono-pyrene counterpart (M-1PY) and control compounds. Upon short UVA irradiation (365 nm) both ligands, in particular M-2PY, efficiently sensitize photoreactions at BrU residues incorporated in G4 structures and give rise to two kinds of photoproducts, namely DNA strand cleavage and covalent ligand–DNA photoadducts. Remarkably, the photoinduced strand cleavage is observed exclusively with G4 structures presenting BrU residues in lateral or diagonal loops, but not with parallel G4-DNA structures presenting only propeller loops. In contrast, the formation of fluorescent photoadducts is observed with all BrU-substituted G4-DNA substrates, with M-2PY giving significantly higher yields (up to 27%) than M-1PY. Both ligand-sensitized photoreactions are specific to BrU-modified G4-DNA structures with respect to double-stranded or stem-loop substrates. Thus, ligand-sensitized photoreactions with BrU-substituted G4-DNA may be exploited (i) as a photochemical probe, allowing “photofootprinting” of G4 folding topologies in vitro and (ii) for covalent trapping of G4 structures as photoadducts with pyrene-substituted ligands.
关键词： covalent photoadducts,pyrene-substituted ligands,photochemical reactions,G-quadruplex,BrU-substituted DNA,DNA strand cleavage
更新于2025-09-09 09:28:46
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Improving the rectifying performance of the pyrene-benzene system by optimizing its hydrocarbon bridge: A first-principles investigation
摘要： We report a computational study on enhancing the rectification ratio (RR) of the pyrene-benzene junction by modifying the structure of its acyclic aliphatic hydrocarbon bridge. The RR values for a series of pyrene-benzene systems with different types of bridges are determined. Notably, the maximum RR of the pyrene-(CH)3-(CH2)3-(CH)3-benzene system is 93.8, and the same hydrocarbon bridge increases the RR of the organic photovoltaic materials pyrene-DMA (N,N-dimethylaniline) and pyrene-DCNB (p-dicyanobenzene) by 10 times and limits reverse current during photo-induced electron transfer. These findings are particularly important for the design of molecular devices where both a high RR and conductivity are desirable. Moreover, they provide new insight into phenomena that indirectly affects the photo-electric conversion efficiency viz. enhancing the RR of the materials.
关键词： molecular electronics,hydrocarbon bridge,photovoltaic materials,pyrene-benzene system,rectification ratio
更新于2025-09-04 15:30:14
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Development of a nanoscale-based optical chemical sensor for the detection of NO radical
摘要： Nitric oxide is one of the most important biochemical parameters in biological processes; it is also known as carcinogenic. There is need for the design of stable and durable solid phase nitric oxide sensors. In this study, we immobilized the nitric oxide sensitive molecules pyrene, tris(2,2’-bipyrdyl)dichlororuthenium(II) hexahydrate (Ru(bipy) 2+ 3 ) , and magnesium phthalocyanine (Mg-Pc) for the first time in polymeric or glassy matrices. We applied silver nanoparticles and ionic liquids in the fabrication process of polymeric electrospun fibers and thin films. We compared their NO sensitivity in micelle solutions that mimic the cell medium by both steady state and lifetime-based fluorescence measurements. Among the tested dyes, the pyrene exhibited the highest response for radicalic NO. The Mg-Pc dye followed pyrene in terms of sensitivity and exhibited increasing fluorescence intensity and lifetime-based response. Lifetime-based response is advantageous and selective as it is not affected by source variations, photo-bleaching, or leaching effects. Another advantage of Mg-Pc dye is that it is not poisonous for organic systems. Presence of the ionic liquid enhanced the sensor response in all of the test moieties. The obtained limit of detection values for pyrene, Ru(bipy) 2+ and Mg-Pc dyes were 0.15 (cid:22) M, 1.54 (cid:22) M, and 0.78 (cid:22) M, respectively.
关键词： electrospinning,Nitric oxide radical,nanomaterials,ruthenium complex,magnesium phthalocyanine,pyrene,time resolved fluorescence
更新于2025-09-04 15:30:14