scholarly journals Proton Triggered Colorimetric and Fluorescence Response of a Novel Quinoxaline Compromising a Donor-Acceptor System

Sensors ◽  
2018 ◽  
Vol 18 (10) ◽  
pp. 3433 ◽  
Author(s):  
Yogesh More ◽  
Sachin Padghan ◽  
Rajesh Bhosale ◽  
Rajendra Pawar ◽  
Avinash Puyad ◽  
...  
Keyword(s):  
Density Functional ◽  
Fluorescence Emission ◽  
Emission Spectra ◽  
Paper Strip ◽  
Time Resolved ◽  
Fluorescence Studies ◽  
Color Changes ◽  
Spectral Changes ◽  
Donor Acceptor ◽  
Strip Test

Quinoxaline-based novel acid-responsive probe Q1 was designed on the basis of a conjugated donor-acceptor (D-A) subunit. Q1 shows colorimetric and fluorometric changes through protonation and deprotonation in dichloromethane. With the addition of the trifluoroacetic acid (TFA), UV-vis absorption spectral changes in peak intensity of Q1 was observed. Moreover, the appearance of a new peaks at 284 nm 434 nm in absorption spectra with the addition of TFA indicating protonation of quinoxaline nitrogen and form Q1.H+ and Q1.2H+. The emission spectra display appearance of new emission peak at 515 nm. The optical property variations were supported by time resolved fluorescence studies. The energy band gap was calculated by employing cyclic voltammetry and density functional calculations. Upon addition of triethylamine (TEA) the fluorescence emission spectral changes of Q1 are found to be reversible. Q1 shows color changes from blue to green in basic and acidic medium, respectively. The paper strip test was developed for making Q1 a colorimetric and fluorometric indicator.

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.

Preparation and Photophysical Properties of All-trans Acceptor–π-Donor (Acceptor) Compounds Possessing Obvious Solvatochromic Effects

2017 ◽  
Vol 70 (9) ◽  
pp. 1048
Author(s):  
Yu-Lu Pan ◽  
Zhi-Bin Cai ◽  
Li Bai ◽  
Sheng-Li Li ◽  
Yu-Peng Tian
Keyword(s):  
Density Functional Theory ◽  
Density Functional ◽  
Photophysical Properties ◽  
Emission Spectra ◽  
Photon Absorption ◽  
Linear Absorption ◽  
Functional Theory ◽  
Two Photon Absorption ◽  
Two Photon ◽  
Donor Acceptor

A series of all-trans acceptor–π-donor (acceptor) compounds (BAQ, SFQ, BLQ, and XJQ) were conveniently synthesised and characterised by infrared, nuclear magnetic resonance, mass spectrometry, and elemental analysis. Their photophysical properties, including linear absorption, one-photon excited fluorescence, two-photon absorption, and two-photon excited fluorescence, were systematically investigated. All the compounds show obvious solvatochromic effects, such as significant bathochromic shifts of the emission spectra and larger Stokes shifts in more polar solvents. Under excitation from a femtosecond Ti : sapphire laser with a pulse width of 140 fs, they all exhibit strong two-photon excited fluorescence, and the two-photon absorption cross-sections in THF are 851 (BAQ), 216 (SFQ), 561 (BLQ), and 447 (XJQ) GM respectively. A combination of density functional theory (DFT) and time-dependent density functional theory (TDDFT) approaches was used to investigate the relationships between the structures and the photophysical properties of these compounds. The results show that they may have a potential application as polarity-sensitive two-photon fluorescent probes.

scholarly journals Synthesis, Characterization and DNA-Binding Affinity of a New Zinc(II) Bis(5-methoxy-indol-3-yl)propane-1,3-dione Complex

2021 ◽  
Vol 14 (8) ◽  
pp. 760
Author(s):  
Luca Scapinello ◽  
Guglielmo Vesco ◽  
Luca Nardo ◽  
Angelo Maspero ◽  
Federico Vavassori ◽  
...  
Keyword(s):  
Metal Ion ◽  
Structural Changes ◽  
Fluorescence Emission ◽  
Spectroscopic Techniques ◽  
Time Resolved ◽  
Fluorescence Studies ◽  
High Affinity ◽  
Drug Substances ◽  
Calf Thymus

The novel zinc(II) µ-oxo-bridged-dimeric complex [Zn2(µ-O)2(BMIP)2] (BMIP = 1,3-bis(5-methoxy-1-methyl-1H-indol-3-yl)propane-1,3-dione), 1, was synthetized and fully characterized. The spectral data indicate a zincoxane molecular structure, with the BMIP ligand coordinating in its neutral form via its oxygen atoms. Structural changes in 1 in dimethylsulfoxide (DMSO) were evidenced by means of spectroscopic techniques including infrared absorption and nuclear magnetic resonance, showing DMSO entrance in the coordination sphere of the metal ion. The resulting complex [Zn2(µ-O)2(BMIP)2(DMSO)], 2, readily reacts in the presence of N-methyl-imidazole (NMI), a liquid-phase nucleoside mimic, to form [Zn2(µ-O)2(BMIP)2(NMI)], 3, through DMSO displacement. The three complexes show high thermal stability, demonstrating that 1 has high affinity for hard nucleophiles. Finally, with the aim of probing the suitability of this system as model scaffold for new potential anticancer metallodrugs, the interactions of 1 with calf thymus DNA were investigated in vitro in pseudo-physiological environment through UV-Vis absorption and fluorescence emission spectroscopy, as well as time-resolved fluorescence studies. The latter analyses revealed that [Zn2(µ-O)2(BMIP)2(DMSO)] binds to DNA with high affinity upon DMSO displacement, opening new perspectives for the development of optimized drug substances.

Excimer Formation in Oligo[2,5-bis(hexadecyloxy)-1,4-phenylene]s Followed by Fluorescence Spectroscopy

2001 ◽  
Vol 66 (10) ◽  
pp. 1473-1489 ◽  
Author(s):  
Drahomír Výprachtický ◽  
Věra Cimrová ◽  
Luďka Machová ◽  
Veronika Pokorná
Keyword(s):  
Fluorescence Spectroscopy ◽  
Hydrophobic Interactions ◽  
Group Analysis ◽  
Fluorescence Emission ◽  
Emission Spectra ◽  
Coupling Reaction ◽  
Fluorescence Emission Spectra ◽  
Time Resolved ◽  
Sandwich Type ◽  
Excimer Formation

Using the steady-state and time-resolved fluorescence spectroscopy, the behavior of "hairy-rod" oligo- and poly[2,5-bis(hexadecyloxy)-1,4-phenylene]s in tetrahydrofuran solutions was investigated. The materials were prepared by the Yamamoto coupling reaction using zinc as a reducing metal, the nickel(II)/triphenylphosphine complex as a catalyst, and 2,2'-bipyridine as a coligand. The appropriate oligomer fractions were separated by fractional precipitation and characterized by GPC and end group analysis. The fluorescence quantum yield of oligomers and polymers increased with their increasing conjugation length. The fluorescence emission spectra of polymers and longer oligomers exhibited one emission maximum at 390 nm with a single-exponential decay and fluorescence lifetimes (τ) around 1 ns. The substitution in positions 2 and 5 forces the adjacent backbone benzene units out of the plane, which results in twist angles 60-80°, and the bulky substituents exclude the cofacial sandwich-type configuration necessary for excimer formation. However, with shorter oligomers, another emission band at 460 nm appeared. Fluorescence decays at 460 nm were found to be double-exponential with longer excited-state lifetimes [e.g. τ1 = 6.9 ns (76%), τ2 = 2.4 ns (24%)]. With shorter oligomers (dimer, trimer), we assume a sandwich-type configuration with sufficiently close interchain distance and hence the excimer can form. Hydrophobic interactions of long aliphatic side chains in a polar medium play an important role in the excimer formation.

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.

A three-step sequence strategy for facile construction of donor–acceptor type molecules: triphenylamine-substituted acenes

2020 ◽  
Vol 98 (1) ◽  
pp. 40-48
Author(s):  
Chen Zhang ◽  
Ming Tang ◽  
Bing Sun ◽  
Weizhou Wang ◽  
Ying Yi ◽  
...  
Keyword(s):  
Density Functional ◽  
Structural Characteristics ◽  
Photophysical Properties ◽  
Phenylboronic Acid ◽  
Fluorescence Emission ◽  
Synthetic Strategy ◽  
Polycyclic Aromatic ◽  
Palladium Catalyzed ◽  
Efficient Construction ◽  
Donor Acceptor

A new synthetic strategy was successfully developed for highly efficient construction of triphenylamine-substituted polycyclic aromatic hydrocarbons (PAHs), including anthracenes, tetraphenes, pentaphenes, and trinaphthylene. These molecules exhibited special structural characteristics, including donor–acceptor–donor (D–A–D) and donor–acceptor (D–A). Diverse aryl iodides coupled well with chlorinated 2-methyl benzaldehydes via a transient ligand-directed C–H bond arylation strategy to furnish various PAH precursors. The subsequent palladium-catalyzed Suzuki cross-couplings with 4-(diphenylamino)phenylboronic acid produced corresponding triphenylamine derivatives. Further, Brønsted acid promoted cycloaromatization generated the triphenylamine-substituted PAHs readily. The photophysical properties was investigated by UV–vis absorption and fluorescence emission spectroscope together with density functional theory (DFT) calculations.

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