E.V. Fedorenko et al.
Journal of Photochemistry & Photobiology, A: Chemistry 412 (2021) 113220
properties of solutions and crystals of two isomers was performed: boron
difluoride 1-(1′-naphthyl)butanedionate-1,3 (β-NAcBF2) and 1-(2′-
naphthyl)butanedionate-1,3 (β-NAcBF2) (Scheme 1).
L-1) were used.
The absorption spectra were registered using a Shimadzu-UV2550
spectrometer (Japan) in cells of a size of 10 × 10 mm. Luminescence
and excitation spectra were registered using a Shimadzu-RF5301 spec-
trometer (Japan). The spectra of the diluted solutions were registered in
a cell of a size of 10 × 10 mm with standard cell positioning. The spectra
of the concentrated solutions were registered in a cell of a size of
10 × 1 mm with frontal cell positioning. Excitation and emission spectra
were recorded on crystals using the front-face configuration of the
spectrofluorimeter. A solution of anthracene in ethanol was used as a
standard for measuring the fluorescence quantum yield (ϕ = 0.27). The
measurements of the fluorescence lifetime by time-correlated single-
photon counting (TCSPC) were performed using a FluoTime 200 device
(PicoQuant, Germany) with a LDH-P-C-375 (370 nm, pulse wide 6 ns
and repetition rate 20 MHz) excitation source and a TimeHarp device as
the SPC controller.
2. Experimental
2.1. Materials
Chloroform, benzene, dichlormethane, and carbon tetrachloride
were purchased from Roskhimreaktiv company and used as received.
Boron trifluoride (acetic acid complex) was purchased from the Acros
Organics and used as received. Acetic anhydride was purified by distil-
lation with a reflux condenser. 1- and 2-acetonaphthones were synthe-
sized according to [43].
2.1.1. Boron difluoride 1-(1′-naphthyl)butanedionate-1,3 (
A solution of 1.09 g of -acetonaphthone in 3 ml acetic anhydride
α-NAcBF2)
α
Fluorescence, phosphorescence and excitation spectra at 77 K were
registered using a spectrofluorimeter Fluorolog 3 (Horiba) using a cry-
ostate. Phosphorescence spectra were recorded under excitation max-
was added to a mixture of 1.78 ml BF3⋅2(CH3COOH) and 5 ml of acetic
anhydride at 45 ◦C for 6 h. After, the mixture was stirred for another 3 h.
Mixture was cooled, the precipitate was filtered and washed with acetic
acid. Yield equaled to 0.89 g (54 %). Recrystallized from acetonitrile (50
%). M. p. 153ꢀ 154 ◦C, Rf = 0.40 (chloroform: hexane 1:2). 1H NMR
400 MHz (CDCl3), δ/ppm: 2.43 (s, 3 H) 6.48 (s, 1 H) 7.49–7.66 (m, 3 H)
7.88–7.94 (m, 2 H) 8.08 (d, J = 8.19 Hz, 1 H) 8.48 (d, J = 8.68 Hz, 1 H).
13C NMR 100 MHz (CDCl3), δ/ppm: 24.75 (s, 1C), 76.67 (s, 1C), 76.99 (s,
1C), 77.19 (s, 1C), 77.31 (s, 1C), 102.07 (s, 1C), 124.56 (s, 1C), 125.11
(s, 1C), 127.02 (s, 1C), 128.56 (s, 1C), 128.90 (s, 1C), 129.89 (s, 1C),
130.20 (s, 1C), 133.84 (s, 1C), 134.97 (s, 1C), 186.96 (s, 1C), 192.45 (s,
ima of 350 and 370 nm for
α-NAcBF2 and β-NAcBF2, respectively.
Excitation pulse was 50 ms long, data collection started at 0.5 ms after
pulse with a 0.2 ms sample window.
IR spectra were recorded using a HEWLETT PACKARD Series 1110
MSD spectrometer in potassium bromide. NMR spectra were recorded
using an Avance 400 MHz high resolution spectrometer (Bruker) on 1H,
13C nuclei at different operating frequencies. The melting point of the
substances synthesized in the present study was determined using a
Büchi melting point model B-540 instrument.
1C). IR (KBr),
ν
/cm–1: 3145, 3062 (C-HAr), 1627 (C10H7), 1598, 1541
(C = O, C = C), 1373 (B–O), 1184 1155 (B–F), 1078, 1053 (B–O). Anal.
2.3. Computational details
calc. for C14H11BF2O2: C 64.66 %, H 4.26 %, Found: C 64.45 %, H 4.22
%.
Quantum chemistry simulation of electronic absorption spectra of
α
-NAcBF2 and β-NAcBF2 was carried out using the GAMESS-US software
2.1.2. Boron difluoride 1-(2′-naphthyl)butanedionate-1,3 (β-NAcBF2)
A solution of 0.425 g β-acetonaphthone in 2 mL acetic anhydride was
added to a mixture of 0.7 ml BF3⋅2(CH3COOH) and 3 ml of acetic an-
hydride at a temperature of 45 ◦C for 6 h. After, the mixture was stirred
for another 3 h. Mixture was cooled, the precipitate was filtered and
washed with acetic acid. Yield equaled to 0.73 g (81 %). Recrystallized
from acetonitrile (59 %). M. p. 182ꢀ 183 ◦C, Rf = 0.33 (chloroform:
complex [44]. The compounds structural parameters, energy charac-
teristics, and electronic structure were determined at complete geome-
try optimization in the 6ꢀ 311 G(d, p) basis by the nonempirical method
and the density functional theory with the exchange-correlation po-
tential B3LYP [45]. Electronic absorption spectra of compounds with
taking into account excited singlet states were calculated by the TDDFT
method in the 6ꢀ 311 G(d, p) basis with the B3LYP potential. Effects
from various solvents were also taken into account using the polarizable
continuum model (PCM). The positions of the maxima of luminescence
spectra were calculated as the energy of transition between S0′ and S1′ in
the optimized geometry of the first excited state. A comparative study of
the structure of the boundary orbitals, the order of transitions, and the
values of the forces of the band oscillators in the absorption spectra
during the transition from the vacuum approximation to the molecule in
the electromagnetic field of the solvent showed no significant differ-
ences (Table 1S). Therefore, only the vacuum approximation was used to
1
hexane 1:2). H NMR 400 MHz (CDCl3), δ/ppm: 2.46 (s, 3 H) 6.73 (s,
1 H) 7.57–7.71 (m, 2 H) 7.88–8.04 (m, 4 H) 8.70 (d, J = 0.98 Hz, 1 H).
13C NMR 100 MHz (CDCl3), δ/ppm: 24.79 (s, 1C), 97.66 (s, 1C), 123.36
(s, 1 C), 127.46 (s, 1C), 127.89 (s, 1C), 128.26 (s, 1C), 129.07 (s, 1C),
129.88 (s, 1C), 129.96 (s, 1C), 131.81 (s, 1C), 132.42 (s, 1C), 136.56 (s,
1C), 182.62 (s, 1C), 192.16 (s, 1C).). IR (KBr),
ν
/cm–1: 3145, 3064 (C-
HAr), 1627 (C10H7), 1598, 1542 (C = O, C = C), 1373 (B–O), 1184 1153
(B–F), 1078, 1049 (B–O). Anal. calc. for C14H11BF2O2: C 64.66 %, H 4.26
%, Found: C 64.40 %, H 4.28 %.
explain the differences in the experimental spectra of the α-NAcBF2 and
2.2. Measurements
β-NAcBF2 isomers.
For spectra measurements, diluted solutions of an optical density of
2.4. X-ray crystallographic analysis
0.1 (C = 1.7·10ꢀ 5 mol L-1) and concentrated solutions (C = 2.6·10-3 mol
Experimental data for
α-NAcBF2 were collected using a BRUKER
Kappa APEX II diffractometer. The intensity data were corrected for
absorption using the multi-scan method.
The structure was determined using direct methods and refined by
least-squares calculation in anisotropic approximation for non-hydrogen
atoms. Hydrogen atoms were added at ideal positions and refined using
a riding model. The data collection and editing, as well as refinement of
unit cell parameters, were performed using the APEX2 program pack-
ages [46]. The structure solution and refinement were performed using
the SHELXTL program packages [47,48].
Crystal data for
α-NAcBF2 (C14H11BF2O2): Pale yellow needles,
Scheme 1. Chemical structure
α
-NAcBF2 and β-NAcBF2.
0.386 × 0.341 × 0.044 mm3, monoclinic, Pc, a = 10.3165(4),
2