Modulation of the solvent-dependent dual emission in 3-hydroxychromones by substituents

Klymchenko, AS
Pivovarenko, VG
Ozturk, T
Demchenko, AP
3-Hydroxychromones (3HCs) are fluorescent dyes, which respond to solvent perturbations by shifts and changes in the relative intensity of the two well-separated bands in the emission spectra. These bands originate from an excited state intramolecular proton transfer (ESIPT) reaction, which can be modulated by different factors, including modi. cations in the 3HC chromophore. In view of the great importance of 3HCs as prospective basic elements of molecular sensors, we have performed the first systematic study on the correlation between 3HC structure and spectroscopic properties. Two series of known and newly synthesized 2-phenyl-3-hydroxychromones and 2-(2-benzo[b]furanyl)-3-hydroxychromones with varied electron-donor substituents, introduced on opposite sides of the chromophore, were compared in solvents of different polarities. The substitution of 2-phenyl for 2-(2-benzo[b] furanyl) and introduction of electron donors on the 2-aryl group not only shift the absorption and fluorescence spectra to the red, but also strongly modulate the ESIPT behavior, resulting in a dramatic increase of the intensity ratio of the two emission bands, I-N*/I-T*. In contrast, introduction of a 7-methoxy group results in exactly the opposite spectroscopic effects. All the studied 3HC dyes demonstrate a linear increase in ln(I-N*/I-T*) with the solvent polarity parameter E-T(30). Substitution of 2-phenyl for 2-(2-benzo[b]furanyl) or introduction of electron donors on the 2-aryl group in 3HC increases the sensitivity of their I-N*/I-T* ratio to solvent polarity and shifts the optimal range of ratiometric polarity sensing to less polar solvents. The opposite effects are observed for 7-methoxy derivatives. These results allow a new generation of two-band fluorescent sensors based on 3HC that operate by the ESIPT mechanism to be proposed. By proper substituents their photophysical and sensing properties can be tuned over broad ranges.


Calculation of the Raman frequencies of lattice modes in the disordered phase II of NH4Br at high pressures
Yurtseven, Hasan Hamit (Physics Essays Publication, 2010-01-01)
The Raman frequencies are calculated here at various temperatures for the nu(7) (56 cm(-1)) and nu(5) (134 cm(-1)) lattice modes in the disordered phase II of NH4Br. The lattice parameter data obtained at zero pressure are used to calculate the Raman frequencies of those modes studied for constant pressures of 0.1, 108, and 637.5 MPa in phase II of the NH4Br crystal. Through the mode Gruumlneisen parameter which is kept constant in the disordered phase II, the Raman frequencies calculated decrease linearly ...
Dependence of the photoluminescence of Tl2InGaS4 layered crystal on temperature and excitation intensity
Hasanlı, Nızamı; Gurlu, O; Aydinli, A; Yilmaz, I (Elsevier BV, 1998-01-01)
The emission band spectra of Tl2InGaS4 layered crystals were investigated in the 10-120 K temperature range and in the 540-860 nm wavelength range using photoluminescence (PL). The peak energy position of the emission band is located at 1.754 eV (707 nm) at 10 K. The emission band has a half-width of 0.28 eV and an asymmetric Gaussian lineshape. The increase of the half-width of the emission band, the blue shift of the emission band peak energy and the quenching of the PL with increasing temperature is expl...
Analysis of Transient Laminar Forced Convection of Nanofluids in Circular Channels
Sert, İsmail Ozan; Sezer Uzol, Nilay; Güvenç Yazıcıoğlu, Almıla; Kakaç, Sadık (2012-11-15)
In this study, forced convection heat transfer Characteristics of nanofluids are investigated by numerical analysis of incompressible transient laminar flow in a circular duct under step change in wall temperature and wall heat flux. The thermal responses of the system are obtained by solving energy equation under both transient and steady-state conditions for hydrodynamically fully developed flow. In the analyses, temperature dependent thermo-physical properties are also considered. In the numerical analys...
Calculation of the Spontaneous Polarization and the Dielectric Constant as a Function of Temperature for KH2PO4
Yurtseven, Hasan Hamit (2012-01-01)
The temperature dependence of the spontaneous polarization P is calculated in the ferroelectric phase (T < T-C) of KH2PO4 (KDP) at atmospheric pressure (T-C = 122 K). Also, the dielectric constant e is calculated at various temperatures in the paraelectric phase (T > T-C) of KDP at atmospheric pressure. For this calculation of P and epsilon, by fitting the observed Raman frequencies of the soft mode, the microscopic parameters of the pure tunnelling model are obtained. In this model, the proton-lattice inte...
ALLAKHVERDIEV, KR; Hasanlı, Nızamı; AYDINLI, A (1995-06-01)
Low-temperature photoluminescence spectra of TlInS2, TlIn0.95 Ga0.05S2 and TlIn0.8Ga0.2S2 layer crystals were studied in the temperature range 14-220 K. The temperature dependencies of bands 2.374eV (A), 2.570 eV (E) and 2.576 eV (F) for TlInS2 are interpreted by supposing that the crystal undergoes structural phase transitions. Band A is considered to come from a donor-acceptor recombination channel.
Citation Formats
A. Klymchenko, V. Pivovarenko, T. Ozturk, and A. Demchenko, “Modulation of the solvent-dependent dual emission in 3-hydroxychromones by substituents,” NEW JOURNAL OF CHEMISTRY, pp. 1336–1343, 2003, Accessed: 00, 2020. [Online]. Available: