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M.E.M. Sakr et al. / Spectrochimica Acta Part A: Molecular and Biomolecular Spectroscopy 232 (2020) 118145
Scheme 1. Preparation of a dye6 (R = 4-MeOC6H4CH=CH-).
hydrazinolysisof4-amino-3-thioxo-3, 4-dihydro-1, 2, 4-triazin-5(2H)-
one as compound (1) could be achieved by its treatment with a boiling
mixture of hydrazine, MeOH/DMF to afford 4-amino-3-hydrazinyl-6-
methyl-1, 2, 4-triazin-5(4H)-one as compound (2). Condensation of 2
with isatoicanhydride as compound (3) in an hydrous boiling dioxane
furnished 3-((4-amino-6-methyl-5-oxo-4,5-dihydro-1,2,4-triazin-3-
yl) amino) quinazoline-2,4 (1H,3H)-dione as compound (4). Compound
(4) was elucidated by spectroscopic data. Thus, the IR spectrum of com-
pound (4) showed absorption bands characteristic for carbonyl groups
at 1500, 1595 and 1640 cm−1. Its 1HNMR spectrum showed a singlet
at 6.18 ppm characteristic for the NH2 protons. In addition, its mass
spectrum showed the parent ion peak at m/z = 419. Coupling of com-
pound (4) with 2-(acetoxymethyl)-6-bromotetrahydro-2H-pyran-
3,4,5-triyl triacetate as compound (5) in pyridine at room temperature
spectra respectively. The wavelengths of excitation were adjusted ac-
cording to the absorption maximum wavelengths for each fluorescence
measurement of dye samples. The amplified spontaneous emission
(ASE) of the dye, various with input pumping power, was measured
using our previous experimental setup [8]. However, the dye samples
were contained in 1 cm optical-path quartz cells that were transversely
pumped by blue laser diode (450 nm). The exciting beam was directed
towards the surface of cell sample with a combination of concave lens
(f = 10 cm) and a cylindrical lens forming a line shape of 1 cm. The
pumping energy (input energy) was measured via a beam splitter
(4%) and the Gentec power meter (ModelQE50) detector head. The
ASE output was focused by convex lens (f = 15 cm) onto Oplenic spec-
trophotometer which was connected to a computer unit for processing
the spectrum. The samples were transversely pumped and were
allowed to emit in the super radiant mode without employing a cavity
mirror, since optical feedback were provided by reflection at host mate-
rial air interface.
gave
2-(acetoxymethyl)-6-(3-((4-amino-6-methyl-5-oxo-4,5-
dihydro-1,2,4-triazin-3-yl) amino)-2,4-dioxo-3,4-dihydro quinazolin-1
(2H)-yl) tetrahydro-2H-pyran-3,4,5-triyl triacetate as compound (6).
Orange colored powder of 50% yield; m.p. 269–270 °C was obtained.
The 1HNMR spectra of compound (6) showed the position of the
anomeric protons at 4.67 with J1t = 9.59 Hz confirmed the β-N-struc-
ture of 6 in addition to the presence of OAc groups at the range
2.09–2.58 ppm. Its IR spectra showed bands at the range
1626–1750 cm−1; IR (KBr), 1626 (CN), 1691 (C=O), 1748 (C=OO)
The photostability of a dye was also measured by using the same ex-
perimental setup. The input energy was kept constant at 100 mW of CW
blue diode laser (λ = 450 nm) for 120 min.
2.3. Photophysical parameters calculations
cm−1
;
1HNMR (DMSO-d6) δ 2.09, 2.18, 2.23, 2.26 (4s, 12H, 4Ac), 3.14
For more deep clarification of the spectroscopic behavior of the dye
and its performance to act as laser dye, some important photo-physical
parameters should be assessed. These parameters such as; absorption
cross section σa [9] and emission cross section σe [10], quantum yield
[11,12]. Also, oscillator strength which is a function of molar absorption
coefficient [13], the attenuation length Λ (λ) [14], the dipole moment
transition (μ12) [15], the decay of excited electrons either radiative
and/or non-radiative [16], the excited state lifetime (τf) [17–19] should
estimate.
By using solvatochromic methods, the dye dipole moments were es-
timated as follow: The solvatochromic method based on linear correla-
tion between the absorption, fluorescence maxima and functions of
solvent polarity [20,21], for determining the dipole moment of ground
and excited state. Lippert–Mataga's Eqs. (1) and (2) [20,22], which is
based on the correlation of difference in energy between both states
(Stokes shift) with the solvent orientation polarizability (Δf), can
(s, 3H, CH3O-4), 3.92 (s, 2H, NH2), 4.21, 4.36, 4.45, 4.59, 4.67 (5s, 7H,
Hpyran, J1t = 9.59 Hz), 6.60–6.88 (m, 10H, H), 8.13 (s, 1H, NH). Anal.
For C35H37N7O13 Calcd.: C, 55.04; H, 4.80; N, 12.84. Found: C, 55.11;
H,4.69; N, 12.77.
2.2. Spectra measurements
Solutions of dye concentrations ranging from 4 × 10−5 M to 1 × 10−6
M were prepared for optical studies. The dye optimum concentration in
ethanol was assessed from its absorption and emission spectra. The op-
timum concentration was 3 × 10−5 M in ethanol. Then, the same con-
centration of dye dissolved into different solvents like hexane, THF,
DMF, DMSO, iso-propanol, ethanol, methanol and ethylene glycol. A
Camspec M501 UV/Vis spectrophotometer and PF-6300 spectrofluo-
rometer were used to measure the absorption and excitation-emission