scholarly journals Non-Typical Fluorescence Effects and Biological Activity in Selected 1,3,4-thiadiazole Derivatives: Spectroscopic and Theoretical Studies on Substituent, Molecular Aggregation, and pH Effects

2019 ◽  
Vol 20 (21) ◽  
pp. 5494 ◽  
Author(s):  
Budziak ◽  
Karcz ◽  
Makowski ◽  
Rachwał ◽  
Starzak ◽  
...  
Keyword(s):  
Charge Transfer ◽  
Density Functional ◽  
Fluorescence Emission ◽  
Emission Spectra ◽  
Ph Effects ◽  
Molecular Aggregation ◽  
Dual Fluorescence ◽  
Fluorescence Emission Spectra ◽  
Biological Studies ◽  
Td Dft

The below article presents the results of spectroscopic research, theoretical (time-dependent density functional theory (TD-DFT)), microbiological, and antioxidative calculations for three compounds from the group of 1,3,4-thiadiazoles: 2-amino-5-phenyl-1,3,4-thiadiazole (TB), 2-amino-5-(2-hydroxyphenyl)-1,3,4-thiadiazole (TS), 2-amino-5-(2-hydroxy-5-sulfobenzoyl)-1,3,4-thiadiazole (TSF). In the fluorescence emission spectra (TS) of solutions with varying concentrations of hydrogen ions, a particularly interesting effect of dual fluorescence was observed. The aforementioned effect was observed even more clearly in the environment of butan-1-ol, relative to the compound’s concentration. Depending on the modification of the resorcylic substituent (TS and TSF), we observed the emergence of two separate, partially overlapping, fluorescence emission spectra or a single emission spectrum. Interpretation of the obtained spectra using stationary and time-resolved spectroscopy allowed the correlation of the effect’s emergence with the phenomenon of molecular aggregation (of a particular type) as well as, above all, the structure of the substituent system. The overlap of said effects most likely induces the processes related to the phenomenon of charge transfer (in TS) and is responsible for the observed fluorescence effects. Also, the position of the –OH group (in the resorcylic ring) is significant and can facilitate the charge transfer (CT). The determinations of the changes in the dipole moment and TD-DFT calculations further corroborate the above assumption. The following paper presents the analysis (the first for this particular group of analogues) of the fluorescence effects relative to the changes in the structure of the resorcylic group combined with pH effects. The results of biological studies also indicate the highest pharmacological potential of the analogue in the case where the effects of dual fluorescence emission are observed, which predisposes this particular group of fluorophores as effective fluorescence probes or potential pharmaceuticals with antimycotic properties.

scholarly journals A Coumarin-Based Fluorescence Probe for Selective Recognition of Cu2+ Ions and Live Cell Imaging

2019 ◽  
Vol 2019 ◽  
pp. 1-7
Author(s):  
Guangjie He ◽  
Nana Ma ◽  
Linlin Li ◽  
Chenyan Xie ◽  
Linlin Yang ◽  
...  
Keyword(s):  
Live Cell Imaging ◽  
Density Functional ◽  
Fluorescence Probe ◽  
Limit Of Detection ◽  
Fluorescence Emission ◽  
Emission Spectra ◽  
Fluorescence Emission Spectra ◽  
Functional Theory ◽  
Photochemical Properties ◽  
Fluorescence Titrations

A new fluorescence probe L was rationally designed and synthesized for the recognition of Cu2+ ions by the combination of coumarin hydrazide and 2-acetylpyrazine. The photochemical properties and selectivity of L for Cu2+ ions in a CH3CN/HEPES (3 : 2, v/v) buffer were investigated by UV-vis absorption and fluorescence emission spectra. A highly selective and sensitive response of L for Cu2+ ions over other competing metal ions was observed with limit of detection in 3 μM. The coordination stoichiometry of L to Cu2+ ions was determined to be 1 : 1 by the UV-vis absorption spectrum, the fluorescence titrations, and density functional theory (DFT) calculations. Moreover, L was applied successfully for recognition of intracellular Cu2+ ions in living cells.

A THEORETICAL STUDY ON DUAL FLUORESCENCE OF 4-DIMETHYLAMINOPYRIDINE BY POLARIZABLE CONTINUUM MODEL

2008 ◽  
Vol 07 (04) ◽  
pp. 821-832 ◽  
Author(s):  
JUAN-QIN LI ◽  
XIANG-YUAN LI ◽  
FENG WANG
Keyword(s):  
Charge Transfer ◽  
Density Functional ◽  
Intramolecular Charge Transfer ◽  
Emission Spectra ◽  
Polarizable Continuum Model ◽  
Transfer Model ◽  
Dual Fluorescence ◽  
Field Methods ◽  
Complete Active Space ◽  
Self Consistent Field

Dual fluorescence spectra of 4-dimethylaminopyridine (DMAP) is investigated using time-dependent density functional theory and complete active space self-consistent field methods. Electronic absorption and emission spectra of DMAP have been investigated in three solvents, that is, cyclohexane, chloroform, and acetonitrile. The present study reveals that the dual fluorescence phenomena of DMAP appear in the cases of acetonitrile and chloroform, but not in cyclohexane. The electronic structures of the ground state and the intramolecular charge transfer states are, therefore, studied in order to reveal the insight of dual fluorescence. Our theoretical results suggest that the twisting of dimethylamino moiety in DMAP is necessary for the intramolecular charge transfer. The mechanism of the dual fluorescence of DMAP is discussed based on the twisted intramolecular charge transfer model and the dual fluorescence phenomenon is explained theoretically.

scholarly journals A new fluorescent chemosensor for fluoride anion based on a pyrrole–isoxazole derivative

2011 ◽  
Vol 7 ◽  
pp. 46-52 ◽  
Author(s):  
Zhipei Yang ◽  
Kai Zhang ◽  
Fangbin Gong ◽  
Shayu Li ◽  
Jun Chen ◽  
...  
Keyword(s):  
Density Functional ◽  
Fluorescence Emission ◽  
Emission Spectra ◽  
Fluoride Anion ◽  
Fluorescence Emission Spectra ◽  
Functional Theory ◽  
Binding Motifs ◽  
H Nmr ◽  
Isoxazole Derivative ◽  
Fluoride Detection

Molecules containing polarized NH fragments that behave as anion-binding motifs are widely used as receptors for recognition and sensing purposes in aprotic solvents. We present here a new example of a receptor, 3-amino-5-(4,5,6,7-tetrahydro-1H-indol-2-yl)isoxazole-4-carboxamide (receptor 1), which contains pyrrole, amide and amino subunits. This receptor shows both changes in its UV–vis absorption and fluorescence emission spectra upon the addition of F−, resulting in highly selectivity for fluoride detection over other anions, such as Cl−, Br−, I−, HSO4 −, H2PO4 − and AcO− in CH3CN. 1H NMR titration, time-dependent density functional theory (TDDFT) calculations and other experiments confirm that the sensing process is brought about by deprotonation of the pyrrole-NH in receptor 1.

The H.G. Smith Award Article: Fluorescent Analogues of NAMI-A: Synthesis, Characterisation, Fluorescent Properties, and Preliminary Biological Studies in Human Lung Cancer Cells

2014 ◽  
Vol 67 (12) ◽  
pp. 1711 ◽  
Author(s):  
Sumy Antony ◽  
Jonathan C. Morris ◽  
Toby D. M. Bell ◽  
Tracey Brown ◽  
Leone Spiccia ◽  
...  
Keyword(s):  
A549 Cells ◽  
Fluorescence Emission ◽  
Emission Spectra ◽  
Fluorescence Probes ◽  
Human Lung Cancer ◽  
Fluorescent Properties ◽  
Fluorescence Emission Spectra ◽  
Biological Studies ◽  
Ru Complexes ◽  
Fluorescent Analogues

Two new fluorescent ruthenium(iii) complexes, namely 7-azaindolium trans-tetrachlorido(7-azaindole)(dimethylsulfoxide)ruthen(iii)ate (F1) and N-[histaminedihydrolium]-1,8-naphthalenecarboximidic trans-tetracholoro(dimethylsulfoxide)(N-[histaminedihydro]-1,8-naphthalenecarboximide)ruthen(iii)ate (F2) and their respective tetramethylammonium analogues (F3 and F4) are reported herein. The compounds were characterised by elemental analysis, mass spectrometry, UV-vis spectrophotometry, and fluorescence spectroscopy. Molar extinction coefficients (ϵmax) and fluorescence emission spectra were compared to evaluate the electronic properties of the synthesised fluorescent analogues, and hence their value as intracellular fluorescence probes. F3 and F4 were synthesised and characterised in order to eliminate fluorescence arising from the counter-cations in F1 and F2 and thus to obtain a fluorescence quantum yield that reflects only a contribution from the metal complex anion. Half-inhibitory concentrations (IC50) were determined for A549 cells exposed to the Ru complexes for 24 h: F3 (203 ± 26 μM) and F4 (185 ± 20 μM).

scholarly journals Exploring the optoelectronic properties of a chromene-appended pyrimidone derivative for photovoltaic applications

2019 ◽  
Vol 17 (1) ◽  
pp. 1167-1172
Author(s):  
Mohammed A. Assiri
Keyword(s):  
Density Functional Theory ◽  
Density Functional ◽  
Photophysical Properties ◽  
Fluorescence Emission ◽  
Emission Spectra ◽  
Solvent Polarity ◽  
Frontier Molecular Orbital ◽  
Electronic Effects ◽  
Fluorescence Emission Spectra ◽  
Functional Theory

AbstractIn the present study, a chromene-appended pyrimidone derivative (PBA) has been synthesized in order to account for the relationship between chemical structure and charge transport properties. The optical properties of PBA were studied in different solvents; it displays a weak emission profile in polar protic solvents but is highly emissive in polar aprotic solvents. Quantum chemical approaches on this molecule were performed in detail to highlight the importance of and to better understand the structural and electronic effects of introducing substituted pyrimidone rings in a polyaromatic molecule to support the development of new optoelectronic and photovoltaic devices. We shed light on the frontier molecular orbital, electron injection, electronic coupling constant, light harvesting efficiency, and photophysical properties of PBA by using density functional theory and time domain density functional theory. The absorption spectra (λa) and fluorescence emission spectra (λf) were computed in different solvents (Methanol, Ethanol, Butanol, Hexane, Chloroform and DMF) at the TD-B3LYP/6-31G** and TD-PBE/6-31G** levels of theory, and it was determined that the TD-B3LYP/6-31G** level is more accurate in the reproduction of experimental λa and λf in various solvents. Furthermore, no significant effect was observed on the λa and λf by changing the solvent polarity.

scholarly journals Design and Synthesis of a Fluorescent Probe Based on Copper Complex for Selective Detection of Hydrogen Sulfide

2021 ◽  
Vol 2021 ◽  
pp. 1-7
Author(s):  
Guanglan Mao ◽  
Chenxi Liu ◽  
Nan Yang ◽  
Linlin Yang ◽  
Guangjie He
Keyword(s):  
Density Functional ◽  
Fluorescence Probe ◽  
Limit Of Detection ◽  
Fluorescence Emission ◽  
Emission Spectra ◽  
Fluorescence Emission Spectra ◽  
Functional Theory ◽  
Design And Synthesis ◽  
Sequential Recognition ◽  
Coordination Configuration

A novel fluorescence probe NA-LCX was rationally designed and synthesized for the sequential recognition of Cu2+ and H2S by the combination of hydroxyl-naphthalene and diformylphenol groups. The response properties of NA-LCX for Cu2+ ions and H2S with “on-off-on” manner were investigated by fluorescence emission spectra. A highly selective and sensitive response of complex NA-LCX-Cu2+ for H2S over other competing amino acids was observed with a limit of detection at 2.79 μM. The stoichiometry of NA-LCX toward Cu2+ ions was determined to be 1 : 1 by the UV-Vis absorption spectrum, and the coordination configuration was calculated by density functional theory (DFT) calculations. Moreover, probe NA-LCX was applied successfully for the recognition of Cu2+ ions and H2S in living cells.

Incorporating two different chromophores onto a silicon atom: the crystal structure and photophysical properties of 9-{4-[(9,9-dimethyl-9H-fluoren-2-yl)dimethylsilyl]phenyl}-9H-carbazole

2015 ◽  
Vol 71 (3) ◽  
pp. 195-198
Author(s):  
Ah-Rang Lee ◽  
Won-Sik Han
Keyword(s):  
Crystal Structure ◽  
Density Functional Theory ◽  
Density Functional ◽  
Crystal Packing ◽  
Photophysical Properties ◽  
Fluorescence Emission ◽  
Emission Spectra ◽  
Fluorescence Emission Spectra ◽  
Functional Theory ◽  
Compound C

The crystal structure of the title bifunctional silicon-bridged compound, C35H31NSi, (I), has been determined. The compound crystallizes in the centrosymmetric space groupP21/c. In the crystal structure, the pairs of aryl rings in the two different chromophores,i.e.9-phenyl-9H-carbazole and 9,9-dimethyl-9H-fluorene, are positioned orthogonally. In the crystal packing, no classical hydrogen bonding is observed. UV–Vis absorption and fluorescence emission spectra show that the central Si atom successfully breaks the electronic conjugation between the two different chromophores, and this was further analysed by density functional theory (DFT) calculations.

Optical Properties and Zinc Nitride Thin Films Prepared Using Magnetron Reactive Sputtering

2014 ◽  
Vol 940 ◽  
pp. 11-15
Author(s):  
Jun Qin Feng ◽  
Jun Fang Chen
Keyword(s):  
Thin Films ◽  
Band Gap ◽  
Near Infrared ◽  
Fluorescence Emission ◽  
Emission Spectra ◽  
Sem Images ◽  
Fluorescence Emission Spectra ◽  
Glass Substrates ◽  
Zinc Nitride ◽  
Direct Band

Zinc nitride films were deposited by ion sources-assisted magnetron sputtering with the use of Zn target (99.99% purity) on 7059 glass substrates. The films were characterized by XRD, SEM and EDS, the results of which show that the polycrystalline zinc nitride thin film can be grown on the glass substrates, the EDS spectrum confirmed the chemical composition of the films and the SEM images revealed that the zinc nitride thin films have a dense structure. Ultraviolet-visible-near infrared spectrophotometer was used to study the transmittance behaviors of zinc nitride thin films, which calculated the optical band gap by Davis Mott model. The results of the fluorescence emission spectra show the zinc nitride would be a direct band gap semiconductor material.

Stress and Phase Transformation Phenomena in Oxide Films: Real-Time Spectroscopic Measurements

1992 ◽  
Vol 271 ◽  
Author(s):  
Gregory J. Exarhos ◽  
Nancy J. Hess
Keyword(s):  
Phase Transformation ◽  
Applied Pressure ◽  
Oxide Films ◽  
Fluorescence Emission ◽  
Emission Spectra ◽  
Film Deposition ◽  
Optical Methods ◽  
Fluorescence Emission Spectra ◽  
Line Intensities ◽  
Deposition Parameters

ABSTRACTIn situ optical methods are reviewed for characterization of phase transformation processes and evaluation of residual stress in solution-deposited metastable oxide films. Such low density films most often are deposited as disordered phases making them prone to crystallization and attendant densification when subjected to increased temperature and/or applied pressure. Inherent stress imparted during film deposition and its evolution during the transformation are evaluated from phonon frequency shifts seen in Raman spectra (TiO2) or from changes in the laser-induced fluorescence emission spectra for films containing rare earth (Sm+3:Y3Al5O12) or transition metal (Cr+3 :Al2O3) dopants. The data in combination with measured increases in line intensities intrinsic to the evolving phase are used to follow crystallization processes in thin films. In general, film deposition parameters are found to influence the crystallite ingrowth kinetics and the magnitude of stress and stress relaxation in the film during the transformation. The utility of these methods to probe crystallization phenomena in oxide films will be addressed.

scholarly journals Fluorescence emission spectra of silver and silver/cobalt nanoparticles

2012 ◽  
Vol 19 (3) ◽  
pp. 943-947 ◽  
Author(s):  
Z. Parang ◽  
A. Keshavarz ◽  
S. Farahi ◽  
S.M. Elahi ◽  
M. Ghoranneviss ◽  
...  
Keyword(s):  
Fluorescence Emission ◽  
Emission Spectra ◽  
Cobalt Nanoparticles ◽  
Fluorescence Emission Spectra
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