Photophysical and theoretical studies on the solvatochromic effects and dipole moments evaluation of substituted 1-phenyl-3-naphthyl-5- (4-ethyl benzoate)-2-pyrazoline

Influence of Temperature on Rotational Dynamics of 3B7D2HC-2-one Molecule in Non-polar, Polar, and Polar Aprotic Solvents

Rotational dynamics of 3-(3H-2l4-benzo[c]isothiazol-2-yl)-7-(diethylamino)-2H-chromen-2-one (3B7D2HC-2-one) is studied using steady-state fluorescence depolarization and time-resolved fluorescence techniques in non-polar, polar and polar aprotic solvents by varying temperatures. Computational calculations are performed using Gaussian 09 software. Over the general solvatochromic method, an advanced thermochromic shift method is used to estimate dipole moments. Experiment rotational diffusion of 3B7D2HC-2-one in methanol indicates slow rotation over the other two solvents. Further, experiment rotational diffusion is analyzed using hydrodynamic and Quasi-hydrodynamic theories. The observed reorientation time follows the trend as predicted by quasi-hydrodynamic models.

Multicolor fluorescence switching material induced by force and acid

A novel D-A-D chromophore TBQM based on triphenylamine, acylhydrazone and dimethylamino was synthesized, and the emission properties of TBQM was studied in solutions as well as in aggregated state. TBQM showed obvious solvatochromism in different solutions. In addition, the reversible multicolor fluorescence switching properties under the stimulation of external forces and acid were also obtained. The fluorescence of TBQM changed from blue to bright blue, and finally to blue-green as the degree of grinding increased, which would recover after being fumigated by CH₂Cl₂. Meanwhile, TBQM could undergo twice protonation after fumigated by TFA. The fluorescence color changed from blue to bright blue, blue-green, and yellow-green until the fluorescence was quenched with the increasing of TFA fumigation time, which can be restored automatically or by TEA fumigation. Moreover, TBQM could be used as an advanced fluorescent anti-counterfeiting ink.

Hot exciplexes in U-shaped TADF molecules with emission from locally excited states

Fast emission and high color purity are essential characteristics of modern opto-electronic devices, such as organic light emitting diodes (OLEDs). These properties are currently not met by the latest generation of thermally activated delayed fluorescence (TADF) emitters. Here, we present an approach, called "hot exciplexes" that enables access to both attributes at the same time. Hot exciplexes are produced by coupling facing donor and acceptor moieties to an anthracene bridge, yielding an exciplex with large T1 to T2 spacing. The hot exciplex model is investigated using optical spectroscopy and quantum chemical simulations. Reverse intersystem crossing is found to occur preferentially from the T3 to the S1 state within only a few nanoseconds. Application and practicality of the model are shown by fabrication of organic light-emitting diodes with up to 32 % hot exciplex contribution and low efficiency roll-off.

Tuning a pyrazoline-based fluorogenic reagent, 3-naphthyl-1-(4-trifluoromethyl)-5-(4-carboxy phenyl)-2-pyrazoline for sensitive precolumn derivatization of aliphatic alcohols and trace analysis by RP-HPLC with fluorescence detection

A new member of the pyrazoline family, 3-naphthyl-1-(4-trifluoromethyl)-5-(4-carboxy phenyl)-2-pyrazoline has been evaluated as a precolumn derivatization reagent for the analysis of primary alcohols using HPLC. The simultaneous separation of eight alcohol derivatives (C₁ -C₈ ) within 15 min was achieved on a reverse-phase C₈ column with an isocratic elution mode. The derivatives were detected with fluorescence at an emission wavelength of 470 nm when excited at 360 nm. The identification of the corresponding derivatives was carried out by LC-MS/MS and all showed their characteristic parent peak in negative ion mode. The proposed method was validated using normal analytical tools and was found to be excellent. As a preliminary application, our method was used to determine ethanol concentration in alcohol-containing chocolates and cough syrup.

Design, synthesis, and photophysics of bi- and tricyclic fused pyrazolines

A three series of bi-cyclic and tri-cyclic functionalised pyrazoline fluorophores with high quantum yields and positive solvato(fluoro)chromism were designed and synthesised by improved method.

Multiple stimulus-responsive behavior of a triphenylamine-substituted acylhydrazone derivative

A triphenylamine-based acylhydrazone derivative (TBHM) was synthesized, and its emission properties either in solution or in the solid state were studied.

Photophysical properties and fluorosolvatochromism of D-π-A thiophene based derivatives

Solvation-dependent photophysical properties of two push-pull thiophene-based compounds with donor-π-acceptor (D-π-A) structures were investigated using absorption, fluorescence emission and time resolved spectroscopy, and supported by different solvation models. Intramolecular charge transfer characteristics of the structurally similar 2-fluoro-4-(5-(4-methoxyphenyl)thiophen-2-yl)benzonitrile (MOT) and 4-(5-(4-(dimethylamino)phenyl)thiophen-2-yl)-2-fluorobenzonitrile (DMAT) were investigated. Significant enhancement of intramolecular charge transfer strength has been observed through molecular structure modification of the electron donating group from a methoxy to dimethylamine group. Ground state absorption spectra show a small red shift of about 10 nm and 18 nm while the fluorescence emission spectra show a large red shift of about 66 nm and 162 nm on changing from the nonpolar cyclohexane to the aprotic polar DMSO for MOT and DMAT, respectively. Dipole moment change from the ground state to the charge transfer excited state is calculated to be 6.6 D in MOT and 9.0 D in DMAT. The fluorescence quantum yield, fluorescence lifetime and the derived radiative and non-radiative rate constants were found to be better correlated to the emission energy rather than any of the solvent properties. Three multi-parametric relationships were used in the interpretation of the specific versus non-specific solute-solvent interactions, namely, Kamlet-Taft, Catalán and Laurence et al. models. The findings of these approaches are used to extract useful information about different aspects of solvent effects on the photophysical properties of the two studied compounds. Kamlet-Taft solvatochromic model indicates that non-specific interactions are dominant in controlling the photophysical properties. Catalán's solvent dipolarity/polarizability parameter is found to play a significant role in solvatochromic behaviour which is also designated by the Laurence model.