Synthesis, IR spectra, crystal structure and DFT studies on 1-acetyl-3-(4-chlorophenyl)-5-(4-methylphenyl)-2-pyrazoline.
ABSTRACT 1-Acetyl-3-(4-chlorophenyl)-5-(4-methylphenyl)-2-pyrazoline has been synthesized and characterized by elemental analysis, IR and X-ray single crystal diffraction. Density functional (DFT) calculations have been carried out for the title compound by using the B3LYP method at the 6-311G** basis set level. The calculated results show that the predicted geometry can reproduce well the structural parameters. Predicted vibrational frequencies have been assigned and compared with experimental IR spectra and they are supported each other. On the basis of vibrational analyses, the thermodynamic properties of the title compound at different temperatures have been calculated, revealing the correlations between C(0)(p, m), S(0)(m), H(0)(m) and temperatures.
[show abstract] [hide abstract]
ABSTRACT: To a certain extent, all cellular, physiological, and pathological phenomena that occur in cells are accompanied by ionic changes. The development of techniques allowing the measurement of such ion activities has contributed substantially to our understanding of normal and abnormal cellular function. Digital video microscopy, confocal laser scanning microscopy, and more recently multiphoton microscopy have allowed the precise spatial analysis of intracellular ion activity at the subcellular level in addition to measurement of its concentration. It is well known that Ca2+ regulates numerous physiological cellular phenomena as a second messenger as well as triggering pathological events such as cell injury and death. A number of methods have been developed to measure intracellular Ca2+. In this review, we summarize the advantages and pitfalls of a variety of Ca2+ indicators used in both optical and nonoptical techniques employed for measuring intracellular Ca2+ concentration.Physiological Reviews 11/1999; 79(4):1089-125. · 26.87 Impact Factor
Article: Fluorescent sensors for Zn(2+) based on a fluorescein platform: synthesis, properties and intracellular distribution.[show abstract] [hide abstract]
ABSTRACT: Two new fluorescent sensors for Zn(2+) that utilize fluorescein as a reporting group, Zinpyr-1 and Zinpyr-2, have been synthesized and characterized. Zinpyr-1 is prepared in one step via a Mannich reaction, and Zinpyr-2 is obtained in a multistep synthesis that utilizes 4',5'-fluorescein dicarboxaldehyde as a key intermediate. Both Zinpyr sensors have excitation and emission wavelengths in the visible range ( approximately 500 nm), dissociation constants (K(d1)) for Zn(2+) of <1 nM, quantum yields approaching unity (Phi = approximately 0.9), and cell permeability, making them well-suited for intracellular applications. A 3- to 5-fold fluorescent enhancement is observed under simulated physiological conditions corresponding to the binding of the Zn(2+) cation to the sensor, which inhibits a photoinduced electron transfer (PET) quenching pathway. The X-ray crystal structure of a 2:1 Zn(2+):Zinpyr-1 complex has also been solved, and is the first structurally characterized example of a complex of fluorescein substituted with metal binding ligands.Journal of the American Chemical Society 08/2001; 123(32):7831-41. · 9.91 Impact Factor
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ABSTRACT: The development and cellular applications of novel fluorescent probes for Zn2+, ZnAF-1F, and ZnAF-2F are described. Fluorescein is used as a fluorophore of ZnAFs, because its excitation and emission wavelengths are in the visible range, which minimizes cell damage and autofluorescence by excitation light. N,N-Bis(2-pyridylmethyl)ethylenediamine, used as an acceptor for Zn2+, is attached directly to the benzoic acid moiety of fluorescein, resulting in very low quantum yields of 0.004 for ZnAF-1F and 0.006 for ZnAF-2F under physiological conditions (pH 7.4) due to the photoinduced electron-transfer mechanism. Upon the addition of Zn2+, the fluorescence intensity is quickly increased up to 69-fold for ZnAF-1F and 60-fold for ZnAF-2F. Apparent dissociation constants (K(d)) are in the nanomolar range, which affords sufficient sensitivity for biological applications. ZnAFs do not fluoresce in the presence of other biologically important cations such as Ca2+ and Mg2+, and are insensitive to change of pH. The complexes with Zn2+ of previously developed ZnAFs, ZnAF-1, and ZnAF-2 decrease in fluorescence intensity below pH 7.0 owing to protonation of the phenolic hydroxyl group of fluorescein, whose pKa value is 6.2. On the other hand, the Zn2+ complexes of ZnAF-1F and ZnAF-2F emit stable fluorescence around neutral and slightly acidic conditions because the pKa values are shifted to 4.9 by substitution of electron-withdrawing fluorine at the ortho position of the phenolic hydroxyl group. For application to living cells, the diacetyl derivative of ZnAF-2F, ZnAF-2F DA, was synthesized. ZnAF-2F DA can permeate through the cell membrane, and is hydrolyzed by esterase in the cytosol to yield ZnAF-2F, which is retained in the cells. Using ZnAF-2F DA, we could measure the changes of intracellular Zn2+ in cultured cells and hippocampal slices.Journal of the American Chemical Society 07/2002; 124(23):6555-62. · 9.91 Impact Factor
Molecules 2008, 13, 2039-2048; DOI: 10.3390/molecules13092039
Synthesis, IR Spectra, Crystal Structure and DFT Studies on
Huan-Mei Guo 1, Lin-Tong Wang 2, Jing-Zhang 3, Pu-Su Zhao 3 and Fang-Fang Jian 1, 3, *
1 Microscale Science institute, Weifang College, Weifang Shandong 261061, P. R. China; E-mail:
firstname.lastname@example.org (Huan-Mei Guo)
2 Department of Chemistry, Weifang College, Weifang Shandong 261061, P. R. China; E-mail:
email@example.com (Lin-Tong Wang)
3 New Materials & Function Coordination Chemistry Laboratory, Qingdao University of Science and
Technology, Qingdao Shandong 266042, P. R. China; E-mails: firstname.lastname@example.org (Jing-
Zhang), email@example.com or firstname.lastname@example.org (Pu-Su Zhao)
* Author to whom correspondence should be addressed. E-mail: email@example.com; Tel.:
+86-0532-84022948; Fax: +86-0532-84023606.
Received: 31 July 2008; in revised form: 19 August 2008 / Accepted: 25 August 2008 / Published: 1
synthesized and characterized by elemental analysis, IR and X-ray single crystal
diffraction. Density functional (DFT) calculations have been carried out for the title
compound by using the B3LYP method at the 6-311G** basis set level. The calculated
results show that the predicted geometry can reproduce well the structural parameters.
Predicted vibrational frequencies have been assigned and compared with experimental IR
spectra and they are supported each other. On the basis of vibrational analyses, the
thermodynamic properties of the title compound at different temperatures have been
calculated, revealing the correlations between C0
p, m, S0
m and temperatures.
Keywords: Synthesis; Crystal structure; Vibrational frequency; DFT.
Molecules 2008, 13
Fluorescent probes are powerful tools in cell biology for the non-invasive measurement of
intracellular ion concentrations . They have found widespread applications, for example, to gauge
intracellular calcium concentrations , to visualize labile zinc [3-4] and iron pools  or as pH
sensors . Among various possible fluorescent probes, pyrazoline-based fluorophores stand out due
to their simple structures and favorable photophysical properties such as large extinction coefficients
and high quantum yields (Фf ≈ 0.6-0.8) . Their attractive applications, including cation- or pH-
sensitive probes, have been described [8-10], and the suitability of pyrazoline fluorophores as probes
in a biological environment has also been explored . Because of its modular nature, the synthesis
of 1,3,5-trisubstituted pyrazoline fluorophores provides a high degree of structural flexibility [7, 12].
On the other hand, density functional theory (DFT) has long been recognized as a better alternative
tool in the study of organic chemical systems than the ab initio methods used in the past , since it
is computationally less demanding for inclusion of electron correlation. Detailed analyses [14-17] on
the performance of different DFT methods have been carried out particularly for equilibrium structure
properties of molecular systems, such as geometry, dipole moment, vibrational frequency, etc. The
general conclusion from these studies is that DFT methods, particularly with the use of nonlocal
exchange-correlation function, can predict accurate equilibrium structure properties. With all this in
mind, after the title compound of 1-acetyl-3-(4-chlorophenyl)-5-(4-methylphenyl)-2-pyrazoline was
synthesized, we performed DFT calculations on it. In this paper, we wish to report the experimental
values as well as the calculated results.
Results and Discussion
Description of the crystal structure
The displacement ellipsoid plot for the title compound with the numbering scheme is shown in
Figure 1. Selected bond lengths and bond angles by X-ray diffraction are listed in Table 1, along with
the calculated bond parameters.
Figure 1. Molecular structure with the atomic numbering scheme for the title compound.
Molecules 2008, 13
Table 1. Selected structural parameters by X-ray and theoretical calculations.
Bond lengths (Å)
Bond angles (°)
Bond angles (°)
The structure of the title compound contains two crystallographically independent molecules in the
asymmetric unit, hereafter named S1 [containing C(1)~C(6) phenyl ring] and S2 [containing
C(19)~C(24) phenyl ring]. In S1 and S2, all of the bond lengths and bond angles are different. For
example, C-Cl bond length of 1.745(4) Å in S1 is longer than that in S2 (1.725(5) Å). In S1, all the
bond lengths in two phenyl rings are in the 1.375(5) ~ 1.390(5) Å range, while in S2, all the bond
lengths in two phenyl rings fall within the 1.374(5) ~ 1.395(5) Å range. Despite some differences, all
of the bond lengths and bond angles in the phenyl rings are in the normal range. As for the two
pyrazolinyl rings, the bond lengths of C=N[1.293(4) Å], C-N [1.483(4) Å ] and N-N [1.395(4) Å] in
S1 are all comparable with those of C=N[1.292(4) Å], C-N [1.488(5) Å ] and N-N [1.398(4) Å] in S2,
and they are all corresponding to those found in similar structures[11,18], respectively. The bond
angles in the two pyrazolinyl rings are also in good agreement with those in the above cited structures
Molecules 2008, 13
[11, 18]. The dihedral angles between the pyrazolinyl ring with the phenyl rings at positions 3 and 5 of
the pyrazoline are 14.00(2) and 83.84(3)° in S1 and 3.54(2) and 78.46(2)o in S2, respectively.
In the crystal lattice, there are two potentially weak intramolecular interactions, along with one
intermolecular interaction (C-H···Y, Y=O, N) . For the two intramolecular interactions, the
distances and angles between donor and acceptor are 2.7991(2) Å and 100.44(2)° for C(18)-
H(18B)···N(1) and 2.7989(2) Å and 108.47(2)° for C(36)-H(36B)···N(3), respectively. For the
intermolecular interaction, the distance and angle between donor and acceptor is 3.4655(2) Å and
166.12(2)° for C(5)-H(5)···O(1) [symmetry code: x, 3/2-y, -1/2+z]. In the solid state, the above
supramolecular interactions stabilize the crystal structure.
Although there are two independent molecules in the asymmetric unit and these two molecules have
some different bond lengths and bond angles in the solid state, they denote the same compound. So,
only one molecular structure was selected to be optimized in the gas phase. DFT calculations were
performed at B3LYP/6-311G** level of theory and the optimized structure was shown in Figure 2.
Some optimized geometric parameters are also listed in Table 1. Comparing the theoretical values with
the experimental ones indicates that most of the optimized bond lengths are slightly larger than the
experimental values, as the theoretical calculations are performed for isolated a molecule in gaseous
phase and the experimental results are for a molecule in a solid state.
Figure 2. One optimized molecular structure for the title compound.
The geometry of the solid-state structure is subject to intermolecular forces, such as van der Waals
interactions and crystal packing forces. The biggest differences of bond lengths and bond angles
between the experimental and the predicted values are -0.0281 Å for Cl(2)-C(21) bond distance and
1.9937° for C(25)-N(3)-N(4) bond angle, which suggests that the calculational precision is satisfactory
 and the B3LYP/6-311G** level of theory is suitable for the system studied here. Based on the
optimized geometries, IR spectra and thermodynamic properties of the title compound are discussed as
Molecules 2008, 13
The experimental IR spectrum is shown in Figure 3. Vibrational frequencies calculated at the
B3LYP/6- 311G** level were scaled by the typical factor 0.96. Some primary calculated harmonic
frequencies are listed in Table 2 and compared with the experimental data. The descriptions
concerning the assignment have also been indicated in the Table 2. The Gauss-view program  was
used to assign the calculated harmonic frequencies. As seen from Table 2, the predicted harmonic
vibration frequencies and the experimental data are very similar to each other. The biggest error occurs
at C-H stretching vibration, with the biggest deviation being 36 cm-1. In a word, the scaled frequencies
of the DFT calculation are close to the corresponding FT-IR vibration data and on the whole the DFT-
B3LYP/6-311G** level can predict the vibrational frequencies for the system studied here.
Figure 3. Experimental IR spectrum of the title compound.
Table 2. Comparison of the observed and calculated vibrational spectra of the title compound.
( B3LYP/6-311G** )
phenyl ring C-H str.
acetyl C-H str.
pyrazolinyl ring C-H str.
methyl group C-H str.
phenyl ring C=C str.+ C=N str.
phenyl ring C=C str.
methyl group C-H bend
phenyl ring C-H bend + pyrazolinyl ring C-H bend
pyrazolinyl ring C-H bend + N-N str.