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Synchronized “Click” and Templated Synthesis of a Fluorescent Pyrene Crown Ether
摘要： The reaction of 6,8-bisethynylpyrene-2-carboxylic acid methyl ester with 1-azido-2-(2-(2-azidoethoxy)ethoxy)ethoxy)ethane using standard “click” chemistry produced a 1+1 crown ether (CPYR). The copper ions used both catalyse the reaction and provide a template for ensuring smooth cyclisation. The X-ray crystal structure of the compound reveals the two triazole groups are non-coplanar with the pyrene moiety. The triazole groups are more co-planar with the pyrene subunit in the first-excited singlet state as revealed by a density functional theory (DFT) calculated molecular structure (B3LYP, 6-311G). Partially structured emission observed in acetonitrile is consistent with the calculation result. In acetonitrile solution the macrocycle CPYR interacts with a Na+ ion to form a complex in which the ion binds with the crown and the pyrene residue.
关键词： pyrene,structure,click,binding,crown ether
更新于2025-11-19 16:46:39
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Optically active crown ether-based fluorescent sensor molecules: A mini-review
摘要： This mini‐review focuses on fluorescent optically active crown ethers (polymeric derivatives are not included) reported in the literature (according to our knowledge), of which enantiomeric recognition ability, and in some cases, also inorganic cation complexation properties, were investigated by the sensitive and versatile fluorescence spectroscopy. These crown ether‐based chemosensors contain various fluorophore signaling units such as binaphthyl, anthracene, pyrene, tryptophan, benzimidazole, terpyridine, acridine, phenazine, acridone, BODIPY, and another conjugated aromatic one.
关键词： enantiomeric recognition,complexation,fluorophore,chemosensor,chiral crown ether
更新于2025-09-23 15:23:52
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Crown-Porphyrin Ligand for Optical Sensors Development
摘要： A novel porphyrin ligand, Zn(II)TPP-BPI-crown (ZnPC), functionalized with two dibenzo-crown-ether moieties was synthesized and tested as cation-sensitive ionophore. Fluorescence studies on ligand sensitivity towards a number of different metal cations (Na+, K+, Li+, Ca2+, Mg2+, Co2+, Cd2+, Pb2+, Cu2+, Zn2+ and NH4+) were carried out first in solution and then inside polymeric membrane optodes. Emission light signal was sufficiently brilliant to be captured by a low-cost computer webcam, while a commercial blue-light LED served as monochromic excitation light source. The influence on the ZnPC optode response of the lipophilic sites functionalization was investigated. The visibly (naked eye) observed color change of sensing material from green to red demonstrated the suitability of the ZnPC-based optodes to perform fast monitoring of Cu(II) ions in the concentration range between 6.6 × 10?7 and 2.4 × 10?2 mol/L with a low detection limit (estimated by s/n = 3 method) of 0.3 mg/L, which is lower than WHO guideline value of 2 mg/L.
关键词： chemical optical sensor,novel Zn(II)-porphyrin ligand functionalized with two dibenzo-crown-ether moieties,naked eye detection of Cu(II) ions
更新于2025-09-23 15:21:01
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A novel crown ether-acylhydrazone turn-on fluorescent chemosensor for Al3+ ion
摘要： A novel fluorescent chemosensor based on crown ether-acylhydrazone (L) was synthesized and characterized. The sensor L exhibited high selectivity and sensitive recognition towards Al3+ through a significant “turn-on” fluorescence response at 444 nm in methanol solution. While, other competitive ions had no such significant effects on the fluorescence emission. The associated spectra behavior might be attributed to the formation of 2:1 L-Al3+ complex and the proposed binding mode of L-Al3+ was demonstrated by the fluorescence titration profiles, Job’s plot, ESI-MS spectrometry, 1H NMR titration and the IR analysis. Besides the high reproducibility of the optical signals, very low detection limit of 0.24 μM was calculated. The association constant (Ks) for L-Al3+ complex was about 5.56×109 ± 8.19×107 M-2. The results of various experiments showed the sensor L followed a turn-on mechanism via of the suppression of C=N isomerization and excited state intramolecular proton transfer (ESIPT) process and the activation of chelation-enhanced fluorescence (CHEF). Theoretical calculations using DFT/B3LYP method was also used to get insight into the sensing mechanism and electronic structure of L. The sensor L could be conceived as an effective and practical fluorescent chemosensor for determination of Al3+.
关键词： chemosensor,binding mode,Al3+,synthesis,crown ether-acylhydrazone
更新于2025-09-10 09:29:36
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Ultrafast Excited State Dynamics of a Stilbene–Viologen Charge Transfer Complex and Its Interaction with Alkanediammonium Salts
摘要： The spectral and thermodynamic properties of charge transfer complexes D?A and D?A?D between (E)-bis(18-crown-6)stilbene (D) and 1,1'-bis(2-ammonioethyl)-4,4'-bipyridinium tetraperchlorate (A) in MeCN were studied. The complex D?A is highly stable, while the complex D?A?D is weakly stable. D?A does not fluoresce due to fast intramolecular processes of direct and reverse electron transfer. The efficiency of D?A fluorescence ignition upon adding alkanediammonium salts depends on the length of a carbon chain. The spectral and kinetic characteristics of D?A and D?A?D CT states were obtained by femtosecond transient absorption spectroscopy. It was established that the characteristic time of back electron transfer in the CT state of D?A?D (770 fs) is significantly higher than that in the CT state of D?A (400 fs). In a number of charge transfer complexes, formed by derivatives of 4,4'-bipyridinium and di-(4-pyridinium)-ethylene with ammonioethyl and ammoniopropyl N-substituents, the rate of back electron transfer depends weakly on the acceptor nature, but is determined by the length of the carbon chain of terminal groups.
关键词： fluorescence,charge transfer complex,ultrafast electron transfer,transient absorption spectroscopy,bis-crown ether
更新于2025-09-04 15:30:14