Study on second harmonic generation of 9-benzylidene-substituted-10-methyl-9,10-dihydroacridines

Article abstract of DOI:10.1016/S1386-1425(01)00461-9

Eight 9-benzylidene-substituted-10-methyl-9,10-dihydroacridine derivatives were synthesized from acridine as starting material and were characterized by ¹H-NMR, ¹³C-NMR, Ms and elemental analysis. The second harmonic generation (SHG) values of these compounds were determined in powder using Nd:YAG as a laser source, as compared with urea powder, and the values of second-order polarizabilities (β_xxx), the values of the composite magnitude (β_CTμg) of molecular hypersusceptibilities and their moment of these compounds were obtained by the solvatochromic method under ground state for everyone. The results showed that SHG value of 10 is higher than that of urea; the β_CTμg of 5 (107.8 × 10^-30 esu) is lower than that of 4-nitro-N,N-dimethylaniline (30 × 10^-30 esu); the β_CTμg of 7 (350.8 × 10^-30 esu) and 10 (244.6 × 10^-30 esu) are higher than that of 4-nitro-N,N-dimethylaniline; the β_CTμg of 8 (3553 × 10^-30 esu), 11 (1187 × 10^-30 esu) and 12 (1163 × 10^-30 esu) are much more higher than that of 4-nitro-N,N-dimethylaniline. The results demonstrated that this series of compounds possesses good second-order nonlinear optical (NLO) property. The regular relationship could not be obtained between electronegativity of substituents (R) attached to benzylidene ring and SHG values or β_CTμg values although the Rs are different in electronegativity and should make an effect on the extent of intramolecular electron-transfer and would consequently influence SHG or β_CTμg. The electron-withdrawing ability of R from benzylidene ring played an important role on λ_max of these compounds.

Full text of DOI:10.1016/S1386-1425(01)00461-9

Spectrochimica Acta Part A 57 (2001) 2729–2736
www.elsevier.com/locate/saa
Study on second harmonic generation of
9-benzylidene-substituted-10-methyl-9,10-dihydroacridines
Hua-Can Song *, Rui-Jiang Jin, Xiang-Li Zheng, Bai-Ning Ying
Department of Chemistry, Zhongshan Uni6ersity, Guangzhou 510275, People’s Republic of China
Received 30 January 2001; accepted 6 February 2001
Abstract
Eight 9-benzylidene-substituted-10-methyl-9,10-dihydroacridine derivatives were synthesized from acridine as start-
ing material and were characterized by 1H-NMR, 13C-NMR, Ms and elemental analysis. The second harmonic
generation (SHG) values of these compounds were determined in powder using Nd:YAG as a laser source, as
compared with urea powder, and the values of second-order polarizabilities (ixxx), the values of the composite
magnitude (iCTmg) of molecular hypersusceptibilities and their moment of these compounds were obtained by the
solvatochromic method under ground state for everyone. The results showed that SHG value of 10 is higher than that
of urea; the iCTmg of 5 (107.8×10−30 esu) is lower than that of 4-nitro-N,N-dimethylaniline (30×10−30 esu); the
iCTmg of 7 (350.8×10−30 esu) and 10 (244.6×10−30 esu) are higher than that of 4-nitro-N,N-dimethylaniline; the
iCTmg of 8 (3553×10−30 esu), 11 (1187×10−30 esu) and 12 (1163×10−30 esu) are much more higher than that of
4-nitro-N,N-dimethylaniline. The results demonstrated that this series of compounds possesses good second-order
nonlinear optical (NLO) property. The regular relationship could not be obtained between electronegativity of
substituents (R) attached to benzylidene ring and SHG values or iCTmg values although the Rs are different in
electronegativity and should make an effect on the extent of intramolecular electron-transfer and would consequently
influence SHG or iCTmg. The electron-withdrawing ability of R from benzylidene ring played an important role on
umax of these compounds. © 2001 Elsevier Science B.V. All rights reserved.
Keywords: 9-Benzylidene-10-methyl-9,10-dihydroacridines; Second harmonic generation; Second-order polarizability
possess high NLO coefficient, short time for re-
sponding to light, little dielectric constant and easy
to be designed and processed. For an application
purpose, it is better to have NLO organic materials
as crystals, however, in the most cases it is not
possible to obtain crystal [3]. Therefore, it is neces-
sary to develop some new methods to evaluate
those NLO organic materials, which are not crys-
tals. Presently, many new methods have been
developed for this purpose, such as electronic field
1. Introduction
With the development of laser technology, to
prepare and study second-order nonlinear optical
(NLO) materials has been the subject of recent
attention [1,2], this is because that organic materials
* Corresponding author. Tel.: +86-20-84110918; fax: +86-
20-84112245.
E-mail address: cedc19@zsu.edu.cn (H.-C. Song).
1386-1425/01/$ - see front matter © 2001 Elsevier Science B.V. All rights reserved.
PII: S1386-1425(01)00461-9

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H.-C. Song et al. / Spectrochimica Acta Part A 57 (2001) 2729–2736
induced method [4,5], solvatochromic method [6],
and Kurtz powder method [7]. A second harmonic
generation (SHG) measurement system for organic
compound powders were built based on the Kurtz
method in our laboratory, and recently we reported
the SHG values of 10-hydrocarbylacridone deriva-
tives measured by this system [8,9]. In this paper we
report SHG values determined by this setup, the
second-order polarizabilities (ixxx), the values of
the composite magnitude (iCTmg) of molecular
hypersusceptibilities and their moment of these
compounds obtained by the solvatochromic
method, and syntheses of another kind of organic
state, the permanent dipole moment of sample
molecule in excited state and the laser frequency,
respectively. Here the ꢀeg could be obtained simply
from the band maximum of the ultra violet (UV)–
visible absorption spectrum of the sample molecule.
veg is related to the intensity of the transition and
could be found out by Eqs. (2) and (3) [11] from
the area under the absorption band:
2yꢀegN0nv2egM
3(2.303)m0ch
area=
(2)
6.909Hr1/2m0ch
2yꢀegN0nM
32.11662×10−61Hr1/2
nMꢀeg
v2eg=
v2eg=
v2eg=
material,
9-benzylidene-10-methyl-9,10-dihy-
droacridine derivatives. Their structures and steps
to synthesize them are outlined in Fig. 1.
(C2 m−1 mol)
3.211662×10−58Hr1/2
nꢀeg
m
(C2 m2)
(3)
2. Results and discussion
where M, N0, n, m0, c and h in Eq. (2) are
concentration of sample, Avogadro’s number, sol-
vent refractive index, speed of light in a vacuum and
the plank constant, respectively. H, r1/2 and m in
Eq. (3) are height of peak, half-width at the middle
of peak, and molecular weight. The values of veg
are calculated with Eq. (3) through the values of
ꢀeg.
Based on equation Eq. (1) [6,10] ixxx may be
obtained,
1.5 h−2v2eg(ve−vg)ꢀe2g
(ꢀe2g−ꢀ2)(ꢀ2eg−4ꢀ2)
ixxx
=
(1)
where ꢀeg, veg, ve, vg and ꢀ are the transition
frequency of sample molecule from ground state to
first excited state, the transition dipole moment
between ground state and excited state, the perma-
nent dipole moment of sample molecule in ground
According to Eq. (1), in order to get ixxx, it is
necessary to found out the values of ve−vg and
presented in Tables 1–5. In our work, only values
Fig. 1.

H.-C. Song et al. / Spectrochimica Acta Part A 57 (2001) 2729–2736
2731
Table 1
The data of ua, ue, H, r1/2, veg and stokes shift in carbon tetrachloridea
Samples
ua (nm)
ue (nm)
H
5
7
8
10
393.5
404
0.024
872.9
630
11
394.3
405
0.041
412.0
640
12
393.3
403
0.016
569.2
612
392.7
401
0.037
1825
527
12.526
20.824
392.9
402.5
455.0
410
0.034
1889
608
12.204
6.749
0.008
2500
2412
14.430
60.844
r1/2 (cm−1
)
Stokes shift
veg (10-30 cm)
ixxx (10−30 m5 c−1
7.418
1.672
6.670
2.73
4.855
3.160
)
a The dielectric constant of carbon tetrachloride is 2.238 (CRC Handbook of Chemistry and Physics Data, 58th; the data in the
following tables were all obtained from this book).
4.612×1029f(ua)mDw1/2Dwmaxh3
of ve−vg are obtained with Bilot–Kawski Eq. (4)
[12] and are listed in Table 5.
iCTmg=
Df(D)
u3au40
Va−Vf=A+B(BK)
f(ua)=
f(D)=
(u02−4ua2)(u20−ua2)
2 (ve−ve)2
B=
hch3
2(D−1)
(2D+1)
(6)
2
(D−1)
(n2−1)
1−(n2−1)
ꢀ
n ꢀ n
BK=
−
}
(2D+1) (2n2+1)
2n2+1
where ua, m, Dw1/2, Dwmax, u0 are absorption wave-
length of sample molecule in excited state, and here,
is assumed as the wavelength of absorption of
sample molecule in dipolar solvent, maximum
absorption coefficient in dipolar solvent, the differ-
ence of the width of peaks at the middle, shift of
maximum absorption, wavelength of base fre-
quency, respectively, h is the same thing as in Eq.
(3).
1−(D−1)
ꢀ n
}
(4)
(2D+1)
where A and B are constants, Va and Vf are wave
numbers of UV–visible absorption and fluores-
cence emission of sample molecule, h is the radius
of a spherical cavity in the solvent occupied by the
sample molecule and it is assumed that h was 0.7
times of the molecular length. D is dielectric con-
stants of solvent.
Dipole moments and bond length were taken
from CRC Handbook of Chemistry and Physics
Data, 60th, F214.
From Eqs. (1) and (5) could be derived:
The umax of 9-(substituent-benzylidene)-10-
methyl-9,10-dihydroacridine in solution originates
from the n-p* electron transition. When an elec-
tron-withdrawing group R is attached to benzyli-
dene ring, the electron-withdrawing conjugating
action of R and the stronger electron-donating
conjugating action of ꢀNꢁCH3 exist at the same
time and the two actions are in the same direction,
that is, a certain extent of intramolecular charge-
transfer would take place in the molecule. As the
intramolecular charge-transfer action makes the
energy level of ‘p*’ orbit lower, little energy is
needed for electron transition from ‘n’ orbit to ‘p*’
orbit, the umax of 9-(substitutent-benzylidene)-10-
methyl-9,10-dihydro-acridine shifts to longer wave-
length. Therefore, umax of this series of compounds
ixxx
1.5(6.6262×10−34 −2
)
J−2 S−2 v2eg(ve−vg)u2e
=
c(1−ꢀ2/ꢀe2)(1–4ꢀ2/ꢀ2e)
ixxx
3.8012(9−1×10−9 C2 m
)
v (ve−vg)u2e
−1 −2
2
eg
=
(1−u2e/u2a×1–4ue2/u2a)
(5)
where ue and ua are wavelength of fluorescence
emission and maximum absorption wavelength of
sample molecule, the values of ixxx could be
calculated from the values of veg, ve−vg and ue
with the Eq. (5).
According to the Eq. (6) [6,13], iCTmg could be
calculated (Table 5):

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H.-C. Song et al. / Spectrochimica Acta Part A 57 (2001) 2729–2736
increases with the increases of the electron-with-
drawing capacity of R. For example, compound 8,
the strong electron-withdrawing action of NO2
gives rise to a greater extent of intramolecular
charge-transfer, which obviously decreases the ‘p*’
orbit energy, so umax of 8 is the biggest one among
these compounds.
For the same electron-withdrawing R, R has a
stronger electron-withdrawing conjugating action
at the p-position than that at the o-or m-position
of benzylidene ring, consequently, umax of 11 is
longer than that of 10.
On the contrary, when an electron-donating R is
attached to benzylidene ring, the electron-donating
conjugating action of R and ꢀNꢁCH3 exist at the
same time, but in the contrary direction. The
coordinating action mentioned above could not
occur in this kind of molecules. For this reason, the
energy level of ‘p*’ orbit of a compound with an
electron-donating R in the benzylidene ring is
higher than that of a compound without an elec-
tron-donating R and much more energy was needed
for electron transition from ‘n’ orbit to ‘p*’ orbit,
as compared with the compound without an elec-
tron-donating R. Thus, the values of umax of these
compounds in chloroform decrease with the in-
crease of the electron-donating capacity of R.
esu) [14]; the iCTmg of 7 (350.8×10−30 esu) and
10 (244.6×10−30 esu) were higher than that of
4-nitro-N,N-dimethylaniline; the bCTmg of
8
(3553×10−30 esu), 11 (1187×10−30 esu) and 12
(1163×10−30 esu) were much more higher than
that of 4-nitro-N,N-dimethylaniline. The reason
for iCTmg value of 8 is higher than that of 4-nitro-
N,N-dimethylaniline is suggested herein that com-
pound 8 has longer conjugating chain than
4-nitro-N,N-dimethylaniline does, the greater ex-
tent of intramolecular charge-transfer would take
place in the molecule of 8 than that in the
molecule of 4-nitro-N,N-dimethylaniline.
The results demonstrated that the ixxx and the
iCTmg of 8 are the highest in the six compounds in
this five solvents, ueg of 5 is the highest in the six
compounds in carbon tetrachloride, chloroform,
1,2-dichloroethane and ethanol. This is because
that NO2 possesses strong electron-withdrawing
action. When NO2 was attached to the ‘p’ posi-
tion of benzyldiene ring, unshared electron-pair
on nitrogen atom could transfer to NO2 along the
conjugation system in the most beneficial method,
which meant that the extent of intramolecular
charge-transfer is the largest one in the six states.
When NO2 was attached to the other position of
the benzyldiene ring, the intramolecular charge-
transfer of 7 could not take place in the most
beneficial method as compared with 5. So ueg, ixxx
and iCTmg of 8 are lower than that of 5.
p-
m-
p-
m-
H
NO2\ NO2\ Cl\
Cl\
umax
(nm)
463.9 400.5 400.1 399.5 394.9
The SHG of 9 is the highest in the six com-
pounds. The iCTmg values of these samples were
obtained in solution in our work, these values
actually reflect the second NLO property. The
SHG values of these samples were measured in
powder. The pattern of crystal of these com-
The iCTmg of 5 (107.8×10−30 esu) was lower than
that of 4-nitro-N,N-dimethylaniline (30×10−30
Table 2
The data of ua, ue, H, r1/2, veg and stokes shift in chloroforma
Samples
5
7
8
10
11
12
ua (nm)
ue (nm)
393.7
405
400.5
413
463.9
415
399.5
410
400.1
411
396.9
409
H
0.058
1881
648
16.02
33.531
0.044
2391
638
13.141
7.337
0.056
2495
2482
21.261
155.23
0.024
1382.6
641
0.042
550
663
7.778
3.984
0.048
1851
715
15.305
32.80
r1/2 (cm-1)
Stokes shift
veg (10−30 cm)
ixxx (10−30 m5 c−1
9.353
2.859
)
a The dielectric constant of chloroform is 4.086.

H.-C. Song et al. / Spectrochimica Acta Part A 57 (2001) 2729–2736
2733
Table 3
The data of ua, ue, H, r1/2, veg and stokes shift in 1,2-dichloroethanea
Samples
ua (nm)
ue (nm)
H
5
7
8
10
399.5
410
0.025
1763
641
10.902
3.884
11
399.3
411
0.049
753
684
12
396.1
409
0.033
2053
796
13.355
24.732
400.9
413
0.037
2004
731
12.203
21.748
402.3
413
464.3
416
0.034
2496
644
14.976
9.744
0.039
3026
2559
19.557
132.35
r1/2 (cm−1
)
Stokes shift
veg (10−30 cm)
ixxx (10−30 m5 c−1
9.972
6.484
)
a The dielectric constant of 1,2-dichloroethane is 9.08.
pounds, a form in which molecules piled up,
certainly causes an effect on the polarization of
molecules, the effect on the polarization of
molecules varies as the pattern of crystal of these
compounds, and the different form of crystal also
gives rise to different extent of intramolecule
charge-transfer. When an organic compound pos-
sesses a higher iCTmg value in solution, it does not
mean that this kind of organic compound is of a
higher SHG value in solid state. So the SHG of 8
is not the highest in the six compounds, although
ueg, ixxx and iCTmg of it are the highest in the six
samples.
5 ml of hexane, then the mixture became yellow.
After the mixture was stirred for 10 min, the
solution of 0.74 g (7.0 mmol) of benzaldehyde in
3 ml of THF was added to this mixture by
dropwise. The mixture was stirred continuously
for other 10 min, then removed the cooling bath,
the mixture was stirred under room temperature
for another 5 h. Evaporated the solvent under
reduced pressure, 250 ml of water was added into
the container. The water layer was extracted with
150 ml of methylene chloride for three times, the
combined extracts were dried over anhydrous
magnesium sulfate. Evaporated the methylene
chloride under reduced pressure to give yellowish
solid product, which was recrystallized in the mix-
ture of methanol and benzene to give 1.00 g
(50.4%) of yellowish product; m.p. 139–141 °C
3. Experimental
3.1. Synthesis of 10-methyl-9-(substituted-benzyl-
dene)-9,10-dihydroacridine
1
(142–144 °C [17]). H-NMR (CdCl3), l 3.48 (s,
3H), 6.70 (s, 1H), 6.80–7.70 (m, 11H), 7.80 (d,
J=7.2 Hz, 2H); Ms for C21H17N(M)+ (Fab), 283;
UV (CHCl3, umax (nm), m), 393.7 (13440), 300.3
(16010), 242.1 (35880).
The 1H-NMR and 13C-NMR spectra (300
MHz) were recorded in CdCl3. Solvents and start-
ing materials were purchased from commercial
sources where available. The salt of N-methyl-
acridinium methylsulfate 2 was prepared as re-
ported [15]; 3 was synthesized as literature [16];
yield 61.0%, m.p. 86–88 °C (uncorrected, litera-
ture 89–91 °C [16]).
3.3. 9-(o-Nitrobenzyldene)-10-methyl-9,10-
dihydroacridine (6)
Compound 6 was obtained from 2.34 g (7.0
mmol) of 3 and 1.06 g (7.0 mmol) of o-nitroben-
zaldehyde as 5 was prepared, expert for the solu-
tion became dark red when the solution of
2-nitrobenzaldehyde in THF was added. The solid
product was recrystallized from the mixture of
methanol and benzene to give 0.8 g (34.8%) of
dark red crystal; m.p. 180–182 °C. 1H-NMR
(CdCl3), l 3.56 (s, 3H), 6.60 (s, 1H), 7.04–7.23
3.2. 9-Benzyldene-10-methyl-9,10-dihydroacridine
(5)
The solution of 2.34 g (7.0 mmol) of 3 in dry
THF was stirred to cool to −78 °C under nitro-
gen atmosphere. To this solution was added the
suspension of 0.45 g (7.0 mmol) of butyllithium in

2734
H.-C. Song et al. / Spectrochimica Acta Part A 57 (2001) 2729–2736
(m, 11H), 8.01 (d, J=6.9 Hz, 1H), 8.20 (t, J=2.1
Hz, 1H); Ms for C21H16N2O2(M)+ (Fab), 328;
anal. calcd. for C21H16N2O2, C, 76.81; H, 4.91; N,
8.53. Found C, 77.11; H, 5.10; N, 8.55. UV
(CHCl3, umax (nm), m), 399.3 (6294), 242.3
(41900).
Hz, 1H), 8.20 (d, J=6.6 Hz, 1H); Ms for
C21H16N2O2 (M)+ (Fab), 328; UV (CHCl3, umax
(nm), m), 468.7 (16510), 305.1 (12750), 241.7
(35430).
3.6. 9-(o,p-Dinitrobenzyldene)-10-methyl-9,10-di-
hydroacridine (9)
3.4. 9-(m-Nitrobenzyldene)-10-methyl-9,10-
dihydroacridine (7)
Compound 9 was prepared as 5 from 2.34 g
(7.0 mmol) of 3 and 1.37 g (7.0 mmol) of 2,4-dini-
trobenzaldehyde, expert for the solution became
brown when the solution of 2,4-dinitrobenzalde-
hyde in THF was added. The solid product was
recrystallized to give 0.91 g (35.0%) of brown
crystal, m.p. 194–196 °C. 1H-NMR (CdCl3), l
3.82(s, 3H), 7.22–7.71 (m, 10H), 8.55 (dd, J=1.6,
1.6 Hz, 2H); 13C-NMR (CdCl3), l 33.98, 115.14,
121.60, 122.86, 128.74, 134.16, 142.91, 178.47; Ms
for C21H15N3O4 (M)+ (Fab), 373; anal. calcd. for
C21H15N3O4, C, 67.56; H, 4.05; N, 11.25. Found,
C, 67.83; H, 4.09; N, 11.12; UV (CHCl3, umax
(nm), m), 399.9 (27840), 381.3 (20870), 276.1
(37730), 257.7 (107400).
Compound 7 was made as 5 synthesized from
2.34 g (7.0 mmol) of 2 and 1.06 g (7.0 mmol) of
3-nitrobenzaldehyde, expert for the solution be-
came red when the solution of 3-nitrobenzalde-
hyde in THF was added. The solid product was
recrystallized from the mixture of methanol and
benzene to give 1.70 g (74.0%) of dark red crystal,
m.p. 179–180 °C (182–185 °C [16]). 1H-NMR
(CdCl3), l 3.56 (s, 3H), 6.64 (s, 1H), 6.68–7.90
(m, 11H), 8.20 (s, 1H). Ms for C21H17N2O2 (M+
H)+ (Fab), 329; UV (CHCl3, umax (nm), m), 401.5
(15850), 285.3 (22420), 241.7 (45520).
3.5. 9-(p-Nitrobenzyldene)-10-methyl-9,10-dihy-
droacridine (8)
3.7. 9-(m-Chlorobenzyldene)-10-methyl-9,10-dihy-
droacridine (10)
Compound 8 was obtained as 5 from 2.00 g (6.0
mmol) of 3, 4 ml (6.4 mmol) of suspension of
butyllithium in THF and 0.91 g (6.0 mmol) of
p-nitrobenzaldehyde, expert for the solution be-
came dark when the solution of p-nitrobenzalde-
hyde in THF was added. The solid product was
recrystallized to give 0.70 g (50.0%) of dark
brown crystal, m.p. 166–168 °C (169–171 °C
[18]). 1H-NMR (CdCl3), l (ppm), 3.60 (s, 3H),
6.62 (s, 1H), 6.74–7.72 (m, 10H), 7.95 (d, J=6.3
Compound 10 was synthesized as 5 from 0.98 g
(7.0 mmol) of m-chlorobenzaldehyde, the product
was recrystallized to give 1.20 g (54.0%) of yellow
pure product, m.p. 115–117 °C; 1H-NMR
(CdCl3), l 3.53 (s, 3H), 6.61 (s, 1H), 6.80 (t,
J=7.4 Hz, 1H), 7.04 (m, 6H), 7.15–7.20 (m, 4H),
7.72 (d, J=7.6 Hz, 1H); 13C-NMR (CdCl3), l
(ppm), 34.02, 112.91, 113.80, 120.47, 121.05,
121.75, 123.93, 126.66, 127.10, 128.67, 128.89,
Table 4
The data of ua, ue, H, r1/2, veg and stokes shift in DMSOa
Samples
ua (nm)
ue (nm)
H
5
7
8
10
407.5
419
0.045
1939
674
15.320
8.478
11
403.3
415
0.048
985
699
12
401.1
415
0.039
1372
835
11.811
20.570
399.3
416
404.1
415
470.3
418
0.046
2020
889
14.732
31.205
0.028
2348
650
13.468
8.059
0.025
2380
2660
13.823
74.445
r1/2 (cm−1
)
Stokes shift
veg (10−30 cm)
ixxx (10−30 m5 c−1
11.219
8.624
)
a The dielectric constant of DMSO is 46.86.

H.-C. Song et al. / Spectrochimica Acta Part A 57 (2001) 2729–2736
2735
Table 5
The data of ua, ue, H, r1/2, veg, ve−veg, stokes shift, ixxx in ethanol, and iCTmg, SHGa
Samples
ua (nm)
ue (nm)
H
5
7
8
10
399.9
423
11
402.1
423
12
391.1
416
394.7
416
0.038
1806
10 222
1297
397.9
414
0.028
3293
8792
977
456.1
415
0.045
2383
14 130
2171
0.041
0.041
0.039
r1/2 (cm−1
)
1696
12 444
1365
867
12 444
1229
1973
11 061
1531
m×10-4 (mol−1 l−1 cm−1
Stokes shift
)
ve−vg
11.576
3.370
13.758
7.788
350.8
0.124
10.597
19.625
108.07
3553
0.061
2.625
14.109
6.540
244.6
1.457
5.250
10.117
6.911
1187
0.084
11.610
14.571
27.728
1163
0.000
veg (10−30 cm)
13.114
23.379
107.8
ixxx (10−30 m5 c−1
iCTmg×10−30 (esu)
SHG (sample/urea)
)
0.000
a The dielectric constant of ethanol is 24.30.
129.18, 129.28, 129.78, 134.25; Ms for C21H16NCl
(M)+ (Fab), 317; anal. calcd. for C21H16NCl, C,
79.36; H, 5.07; N, 4.41. Found, C, 79.08; H, 5.00;
N, 4.44; UV (CHCl3, umax (nm), m), 399.5 (15240),
301.9 (15690), 263.5 (19660), 241.3 (42400).
NMR (CdCl3), l 3.50 (s, 3H), 3.81 (s, 3H), 6.64
(s, 1H), 6.78–6.81 (m, 3H), 6.98–7.06 (m, 3H),
7.26–7.29 (m, 4H), 7.37 (m, 1H), 7.69 (d, J=6.3
Hz, 1H); 13C-NMR (CdCl3), l 33.92, 55.60,
112.68, 113.57, 114.01, 120.33, 121.63, 122.89,
123.79, 128.13, 128.65, 129.05, 130.10, 158.54; Ms
for C22H19NO (M)+ (Fab), 313; UV (CHCl3, umax
(nm), m), 394.9 (15250), 303.3 (15910), 263.5
(21830), 241.7 (42530).
3.8. 9-(p-Chlorobenzyldene)-10-methyl-9,10-dihy-
droacridine (11)
This compound was obtained from 2.34 g (7.0
mmol) of 3 and 0.98 g (7.0 mmol) of p-chloroben-
zaldehyde as 6, expert for the solution became
orange when the solution of p-chlorobenzalde-
hyde in THF was added. It was recrystallized
from the mixture of methanol and benzene to give
1.60 g (72.0%) of orange crystal, m.p. 127–
4. The determination of SHG values
Using Nd:YAG (1.06 mm) as a laser source, the
conditions for measuring SHG values of 9-(substi-
tuted-benzylidene)-10-methyl-9,10-dihydroacrid-
ines were examined. The pulse energy of incidence
to the powder sample surface was about 6.5×
10−3 J. The light area of incidence to the sample
surface was 0.02 mm2. The thickness of the sam-
ple was about 0.1 mm, and the sample was placed
in between two pieces of glass. Fluorescence back-
ground was glass piece, and thickness of the glass
piece was all the same. Urea was used as contrast
sample (urea, analytical reagent, was ground).
SHG value for 9-(substituted-benzylidene)-10-
methyl-9,10-di-hydroacridines measured by this
way is a quantity of times of the SHG value of
urea. The SHG values of 9-(substituted-benzyli-
dene)-10-methyl-9,10-dihydroacridines were listed
in Table 5, Fig. 2.
1
129 °C (130–132 °C [18]). H-NMR (CdCl3), l
3.52 (s, 3H), 6.60 (s, 1H), 6.70–7.41 (m, 9H), 7.80
(d, J=6.9 Hz, 2H); Ms for C21H16NCl (M)+
(Fab), 317; UV (CHCl3, umax (nm), m), 399.9
(15780), 303.7 (14870), 277.3 (11520), 241.1
(41150).
3.9. 9-(p-Methoxybenzyldene)-10-methyl-9,10-di-
hydroacridine (12)
Compound 12 was obtained from 2.34 g (7.0
mmol) of 3 and 0.95 g (7.0 mmol) of p-methoxy-
benzaldehyde as 6, the solid product was recrys-
tallized from the mixture of methanol and
benzene to give 1.10 g (51.40%) of yellow crystal
product; m.p. 150–152 °C (155–156 °C [16]). 1H-

2736
H.-C. Song et al. / Spectrochimica Acta Part A 57 (2001) 2729–2736
01) and the National Natural Science foundation
for Doctors of Guangdong Province.
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The concentrations of 9-(substituted-benzyli-
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ml−1, the n values of the solution of samples were
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3.
Acknowledgements
This work was supported by the Scientific and
Technical Commission of Guangzhou (98-J-013-