Open Access

Synthesis, solvatochromism and crystal structure of 5-Methoxy-5,6-diphenyl-4,5-dihydro-2H −1,2,4-triazine-3-thione

Chemistry Central Journal20137:130

https://doi.org/10.1186/1752-153X-7-130

Received: 31 March 2013

Accepted: 17 July 2013

Published: 28 July 2013

Abstract

Background

For the development of properties in molecular crystals, such as electrical conductivities, magnetic properties, or non-linear optical properties, not only the electronic properties of molecules themselves matter, but also the molecular arrangements in the crystals are very important. Therefore, the design of the crystal structures and the control of molecular arrangements have attracted much attention in recent years. Among various ligands, triazine moieties have been especially interesting because of their biological, pharmacological and medicinal properties.

Results

Crystal structure of 5-Methoxy-5,6-diphenyl-4,5-dihydro-2H-1,2,4-triazine-3-thione is Monoclinic, which consists of space group P21/c with a = 9.699(1), b = 8.500(1), c = 18.044(2) Å, β = 101.290(7)° and Z = 4, R1 = 0.0371 and wR2 = 0.1008 with 2456 reflections (I > 2σ(I)). Intermolecular H bonds between NH groups are acting as donors and S atoms as acceptors. There are also shorted face-to-face as well as edge to face π-π stacking interactions between the parallel aromatic rings. The behavior of solvatochromic of the mentioned compound that involved interhydrogen bonding was investigated by studying its electronic absorption spectra in pure organic solvents of different characters.

Conclusions

The crystal structure of C16H15N3OS, shows the expected face-to-face π-π stacking interactions between aromatic rings of the neighbor chains in this compound. The centroid–centroid distance between the aromatic rings is 3.325 Å. It was found that the monomer of the ligand 5-Methoxy-5,6-diphenyl-4,5-dihydro-2H-1,2,4-triazine-3-thione, further extends into 3D networks via hydrogen bonding and pi-pi stacking interactions. The solvatochromic behavior of the title compound was also investigated by studying its spectra in a selection of different organic solvents. While progressing from the non-polar solvent to the polar one, the main intense band at 310 nm, which is due to the π–π* transition, was red shifted by 13 nm. Thus, the title compound showed positive solvatochromic behavior.

Keywords

Triazine Thione Hydrogen bond Electronic absorption spectra Solvatochromic Crystal structure X- ray

Introduction

Numerous compounds containing the 1,2,4-triazine moieties are well known in natural materials and show interesting biological, pharmacological and medicinal properties. One of the important classes of N-containing heterocycles is the 3,5,6-trisubstituted-1,2,4-triazines. Some of them can be active as blood platelet aggregation inhibitors and others exhibit antiviral inhibitory activity (against influenza viruses for example), significant activity towards leukaemia and ovarian cancer, and anti-HIV activity [14]. Therefore, the design of molecule structures and control of molecular arrangements have attracted much attention in recent years [5]. In this paper, we wish to report the crystalline structure of 5-Methoxy-5,6-diphenyl-4,5-dihydro-2H-1,2,4-triazine-3-thione (Figure 1). In addition to structural, solvatochromic properties of the mentioned molecule are discussed.
Figure 1

Chemical structure of 5-Methoxy-5,6-diphenyl-4,5-dihydro-2 H -1,2,4-triazine-3-thione.

Results and discussion

The crystal structure 5-Methoxy-5,6-diphenyl-4,5-dihydro-2H-1,2,4-triazine-3-thione was solved by direct methods (SIR97) [6] and refined by Full-matrix least squares using the program SHELXTL-97 [7]. The H atoms were refined isotropically. The data had been collected by using a STOE IPDSII. The molecular structure of the title compound is presented in Figure 2. The corresponding crystal and structure refinement data are summarized in Table 1 and all atomic coordinates and equivalent isotropic displacement parameters are given in Table 2. The compound crystallizes in the monoclinic space group P21/c with a = 9.699(1), b = 8.500(1), c = 18.044(2) Å, β = 101.290(7)° and Z = 4. The crystal structure was solved to final values R1 = 0.037 (for 2456 observed rfls. {I > 2σ[I]}) and wR2 = 0.102 (all data), see Additional file 1: Original X-ray analysis data by CIF format.
Figure 2

The ORTEP diagram triazine-3-thione of 5-Methoxy-5,6-diphenyl-4,5-dihydro-2 H -1,2,4- triazine-3-thione.

Table 1

Crystal data and structure refinement details for 5-Methoxy-5,6-diphenyl-4,5-dihydro-2 H -1,2,4-triazine-3-thione

Empirical formula

C16H15N3OS

Formula weight

297.37

Temperature

193(2) K

Wavelength

0.71069 Å

Crystal system, space group

monoclinic, P21/c

Unit cell dimensions

a = 9.699(1) Å

 

b = 8.500(1) Å β = 101.290(7)°

 

c = 18.044(2) Å

Volume

1458.8(3) Å3

Z, Calculated density

4, 1.354 Mg/m3

Absorption coefficient (MoKα )

0.224 mm-1

F(000)

624

Crystal size

0.6 × 0.5 × 0.5 mm

θ range for data collection

2.14 to 25.66 deg.

Limiting indices

−11 < =h < =11, -10 < =k < =10, -21 < =l < =21

Reflections collected / unique

2618 / 2456 [R(int) = 0.0396]

Completeness to theta = 28.04

95.0%

Absorption correction

Semi-empirical from equivalents

Refinement method

Full-matrix least-squares on F2

Data / restraints / parameters

2618 / 0 / 251

Goodness-of-fit on F2

1.062

Final R indices [for 2456 rfls with I > 2σ(I)]

R1 = 0.0371, wR2 = 0.1008

R indices (all data)

R1 = 0.0391, wR2 = 0.1024

Largest diff. peak and hole

0.322 and −0.305 e. Å-3

(Δ/δ)max

0.001

Table 2

Atomic coordinates (Å × 10 4 ) and equivalent isotropic displacement parameters (Å 2 × 10 3 ) for 5-Methoxy-5,6-diphenyl-4,5-dihydro-2 H -1,2,4-triazine-3-thione

 

X

Y

Z

U(eq)

C(1)

−696(15)

3792(16)

7896(9)

22 (3)

C(2)

−1824(14)

2391(16)

8841(8)

21 (3)

C(4)

447(17)

1973(2)

9603(12)

35 (4)

C(5)

−3268(14)

1621(17)

8654(9)

22 (3)

C(6)

−3661(16)

440(18)

9104(10)

28(4)

C(7)

−5008(17)

−187(2)

8934(11)

34 (4)

C(8)

−5965(17)

366(2)

8323(11)

34 (4)

C(9)

−5577(18)

1524(2)

7869(11)

35 (4)

C(10)

−4230(17)

2147(19)

8036(10)

29 (4)

C(11)

−1928(14)

4053(17)

9152(9)

21 (3)

C(12)

−2516(14)

4336(18)

9839(9)

23 (3)

C(13)

−2303(16)

3307(2)

10454(9)

28 (4)

C(14)

−2771(18)

3707(2)

11109(10)

32 (4)

C(15)

−3463(17)

5101(2)

11161(10)

34 (4)

C(16)

−3700(17)

6122(2)

10550(11)

32 (4)

C(17)

−3235(15)

5741(19)

9895(10)

27 (3)

N(1)

−1237(13)

2508(15)

8152(8)

24 (3)

N(2)

−907(14)

5145(15)

8234(8)

27 (3)

N(3)

−1504(13)

5298(14)

8857(8)

25 (3)

S(1)

161(4)

3790(4)

7165(2)

29 (17)

O(1)

−959(10)

1409(12)

9364(6)

24 (3)

U(eq) is defined as one third of the trace of the orthogonalized Uij tensor.

The dihedral angle between the planes of the triazine and two phenyl groups are 32.91 Å and 47.58 Å. The dihedral angle between the methoxyl group and the triazine is 61.69 Å. As shown in Figure 3, intermolecular hydrogen bonds are formed with NH groups acting as donors and S atoms as acceptors, N-HS. The corresponding distances and angles for the hydrogen bonds are given in Table 3. There are both face-to-face and edge to face π-π stacking interactions between aromatic rings [8], as shown in Figure 3. The face-to-face and edge to face interplanar distances are 3.325 Å, appreciably shorter than the normal π- π stacking, and 3.704 Å, respectively.
Figure 3

Unit cell plot of 5-Methoxy-5,6-diphenyl-4,5-dihydro-2 H -1,2,4-triazine-3-thione showing hydrogen bonding and π-π stacking interactions between these molecules.

Table 3

Hydrogen bond distances and angels (in Å and °, respectively) of 5-Methoxy-5,6-diphenyl-4,5-dihydro-2H-1,2,4-triazine-3-thione

D-H

d(D-H)

d(H…A)

d(D…A)

DHA

A

N(2)-H(2 N)

0.924

2.398

3.293

163.82

S(1) [−x,1/2 + y,1.5-z]

The electronic absorption spectra of 5-Methoxy-5,6-diphenyl-4,5-dihydro-2H-1,2,4-triazine-3-thione was studied in organic solvents of different polarities, viz. Hexane, CCl4, CHCl3, C2H5OH, CH3OH, DMF, CH3CN, DMSO (Figure 4). This was done with the intention to investigate the solvatochromic behavior of this compound. While moving from the non-polar solvent to the polar one, the main intense band at 310 nm, which is due to the (π–π*) transition, is red shifted by 13 nm. Therefore, the absorption band of the title compound corresponding to the π–π* transition, shifts to longer wavelengths with an increase of dielectric constant of the solvents. This suggests stabilization of the electronic excited state relative to the ground state. Thus, the title compound showed positive solvatochromic behavior [9, 10].
Figure 4

The electronic absorption spectra of a 3.8 × 10 -5 mol liter -1 5-Methoxy-5,6-diphenyl-4,5-dihydro-2 H -1,2,4-triazine-3-thione in organic solvents:(1)C 6 H 12 (2)CCl 4 (3)CHCl 3 (4)EtOH (5)MeOH (6)DMF (7)CH 3 CN (8)DMSO.

Conclusions

In summary, a single crystal of 5-Methoxy-5,6-diphenyl-4,5-dihydro-2H-1,2,4-triazine-3-thione was prepared. The synthesized compound was characterized by X-ray analysis.

The packing of the resulting crystal clearly revealed that a one-dimensional network is formed owing to the presence of intermolecular weak hydrogen-bonding and S · · · H interactions between the parallel molecules. Also, there are face-to-face π-π stacking interactions between aromatic rings of the neighbor chains in this compound.

Further studies have been conducted for recording the electronic absorption spectra of this molecule in organic solvents of different polarities. The observation of the spectroscopic behavior in the presence of organic solvents indicates that this compound has a positive solvatochromic.

Experimental

The title compound was prepared by reaction of a solution of thiosemicarbazide (15 mmol) in methanol with a solution of HCl (30 cm3, 2 M), 1 cm3 of concentrated HCl and a solution of benzyl (15 mmol) in methanol at room temperature to form 5-Methoxy-5,6-diphenyl-4,5-dihydro-2H-1,2,4-triazine-3-thione [6]. M. P. = 232-233°C, Scheme 1, The branched tube method was used for the preparation of suitable single crystals [4]. The title compound (0.2 g) was placed in one arm of a branched tube, acetonitrile was carefully added to fill both arms, the tube sealed and the compound containing arm immersed in a bath at 60°C, while the other one was at ambient temperature. After 7 days, the suitable crystals for X-ray analysis of 5-Methoxy-5,6-diphenyl-4,5-dihydro-2H-1,2,4-triazine-3-thione were deposited in the cooler arm which was filtered off, washed with ether, and air dried.
Scheme 1

The synthesis procedure of the title compound.

Declarations

Acknowledgements

This work was supported by grants from the Lorestan University Research Council.

Authors’ Affiliations

(1)
Department of Chemistry, Lorestan University

References

  1. El-Gendy Z, Morsy JM, Allimony HA, Abdel- Monem WR, Abdel-Rahman RM: Synthesis of heterobicyclic nitrogen systems bearing a 1,2,4-triazine moiety as anticancer drugs: part IV. Phosphorus, Sulfur, and Silicon and the Relat Elem. 2003, 178: 2055-2071. 10.1080/10426500390228738.View ArticleGoogle Scholar
  2. Abdel-Rahman RM, Morsy JM, Hanafy F, Amene HA: Synthesis of heterobicyclic nitrogen systems bearing the 1,2,4-triazine moiety as anti-HIV and anticancer drugs: part I. Pharm. 1999, 54: 347-351.Google Scholar
  3. Haque RA, Iqbal MA, Khadeer Mohammad B, Majid AMSA, Abdul Hameed ZA: Design, synthesis and structural studies of meta-xylyl linked bis- benzimidazolium salts: potential anticancer agents against 'human colon cancer. Chem Cent J. 2012, 6: 68-10.1186/1752-153X-6-68.View ArticleGoogle Scholar
  4. Rezaei B, Niromand L, Alizadeh K, Retailleau P: Synthesis and crystal structure of 1-p-tolyl-3-(3-(trifluoromethyl)phenyl)- triaz-1-ene 1-oxide. Xray Struct Anal Online. 2012, 28: 37-38. 10.2116/xraystruct.28.37.View ArticleGoogle Scholar
  5. Braga D, Grepioni F, Desiraju GR: Crystal engineering and organometallic architecture. Chem Rev. 1998, 98: 1375-1405. 10.1021/cr960091b.View ArticleGoogle Scholar
  6. Altomare A, Burla MC, Camalli M, Cascarano GL, Giacovazzo C, Guagliardi A, Moliterni AGG, Polidori G, Spagna R: A new tool for crystal structure determination and refinement. J Appl Crystallogr. 1999, 32: 115-119. 10.1107/S0021889898007717.View ArticleGoogle Scholar
  7. Sheldrick GM: Programs for crystal structure analysis (release 97–2). 1998, Tammanstrasse 4, D-3400 Göttingen, Germany: Institut für Anorganische Chemie der UniversitätGoogle Scholar
  8. Janiak C: A critical account on π–π stacking in metal complexes with aromatic nitrogen-containing ligands. Chem Soc Dalton Trans. 2000, 21: 3885-3896.View ArticleGoogle Scholar
  9. Kim JJ, Funabiki K, Muramatsu H, Shibata K, Kim SH, Shiozaki H, Hartmannd H, Matsui M: Negative solovatochromism of azo dyes derived from (dialkylamino)thiazole dimmers. Chem Commun. 2000, 9: 753-754.View ArticleGoogle Scholar
  10. Ohshima A, Momotake A, Arai TJ: Photochromism, thermochromism, and solvatochromism of naphthalene-based analogues of salicylideneaniline in solution. Photoch Photobio A. 2004, 162: 47-479.View ArticleGoogle Scholar

Copyright

© Rezaei and Fazlollahi; licensee Chemistry Central Ltd. 2013

This article is published under license to BioMed Central Ltd. This is an Open Access article distributed under the terms of the Creative Commons Attribution License (http://creativecommons.org/licenses/by/2.0), which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.