3,5-Diphenyl-1-(quinolin-2-yl)-4,5-dihydro-1H-pyrazol-5-ol

Muhd Hidayat bin Najib; Ai Ling Tan; David J Young; Seik Weng Ng; Edward R T Tiekink

doi:10.1107/S1600536812029340

. 2012 Jul 4;68(Pt 8):o2310–o2311. doi: 10.1107/S1600536812029340

3,5-Diphenyl-1-(quinolin-2-yl)-4,5-dihydro-1H-pyrazol-5-ol

Muhd Hidayat bin Najib ^a, Ai Ling Tan ^a, David J Young ^a,^‡, Seik Weng Ng ^b,^c, Edward R T Tiekink ^b,^*

PMCID: PMC3414180 PMID: 22904787

Abstract

In the title compound, C₂₄H₁₉N₃O, the pyrazole ring is close to being planar (r.m.s. deviation of the five fitted atoms = 0.062 Å), and each of the N-bound quinoline ring [dihedral angle = 9.90 (7)°] and the C-bound phenyl ring in the 3-position is close to being coplanar [dihedral angle = 8.87 (9)°]. However, the phenyl ring in the 5-position forms a dihedral angle of 72.31 (9)°. The hydroxy group forms an intramolecular hydrogen bond to the quinoline N atom. In the crystal, molecules are connected into supramolecular layers two molecules thick in the bc plane by C—H⋯O and C—H⋯π interactions.

Related literature

For applications of coordination complexes of hydrazones as organic light emitting diodes and supramolecular magnetic clusters, see: Zhang et al. (2011 ▶, 2012 ▶). For the synthesis of hydrazones, see: Gupta et al. (2007 ▶). For background to and the synthesis of the target molecules, see: Najib et al. (2012a ▶,b ▶,c ▶)

Experimental

Crystal data

C₂₄H₁₉N₃O
M _r = 365.42
Monoclinic,
a = 30.505 (2) Å
b = 7.8881 (4) Å
c = 16.5191 (12) Å
β = 113.718 (9)°
V = 3639.1 (4) Å³
Z = 8
Mo Kα radiation
μ = 0.08 mm⁻¹
T = 100 K
0.35 × 0.30 × 0.25 mm

Data collection

Agilent SuperNova Dual diffractometer with an Atlas detector
Absorption correction: multi-scan (CrysAlis PRO; Agilent, 2012 ▶) T _min = 0.784, T _max = 1.000
12177 measured reflections
4209 independent reflections
3419 reflections with I > 2σ(I)
R _int = 0.033

Refinement

R[F ² > 2σ(F ²)] = 0.048
wR(F ²) = 0.130
S = 1.07
4209 reflections
257 parameters
1 restraint
H atoms treated by a mixture of independent and constrained refinement
Δρ_max = 0.30 e Å⁻³
Δρ_min = −0.32 e Å⁻³

Data collection: CrysAlis PRO (Agilent, 2012 ▶); cell refinement: CrysAlis PRO; data reduction: CrysAlis PRO; program(s) used to solve structure: SHELXS97 (Sheldrick, 2008 ▶); program(s) used to refine structure: SHELXL97 (Sheldrick, 2008 ▶); molecular graphics: ORTEP-3 for Windows (Farrugia, 1997 ▶) and DIAMOND (Brandenburg, 2006 ▶); software used to prepare material for publication: publCIF (Westrip, 2010 ▶).

Supplementary Material

Crystal structure: contains datablock(s) global, I. DOI: 10.1107/S1600536812029340/sj5251sup1.cif

e-68-o2310-sup1.cif^{(21.8KB, cif)}

Structure factors: contains datablock(s) I. DOI: 10.1107/S1600536812029340/sj5251Isup2.hkl

e-68-o2310-Isup2.hkl^{(206.3KB, hkl)}

Supplementary material file. DOI: 10.1107/S1600536812029340/sj5251Isup3.cml

Additional supplementary materials: crystallographic information; 3D view; checkCIF report

Table 1. Hydrogen-bond geometry (Å, °).

Cg1 and Cg2 are the centroids of the C1–C6 and N1,C1,C6–C9 rings, respectively.

D—H⋯A	D—H	H⋯A	D⋯A	D—H⋯A
O1—H1o⋯N1	0.87 (1)	2.15 (2)	2.8149 (19)	133 (3)
C3—H3⋯O1ⁱ	0.95	2.50	3.298 (2)	142
C11—H11A⋯Cg1ⁱⁱ	0.99	2.92	3.8528 (18)	157
C17—H17⋯Cg2ⁱⁱⁱ	0.95	2.58	3.4426 (18)	151
C24—H24⋯Cg2ⁱⁱ	0.95	2.97	3.6239 (18)	127

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Symmetry codes: (i) Inline graphic ; (ii) ; (iii) .

Acknowledgments

We gratefully acknowledge funding from the Brunei Research Council, and thank the Ministry of Higher Education (Malaysia) for funding structural studies through the High-Impact Research scheme (UM.C/HIR/MOHE/SC/12).

supplementary crystallographic information

Comment

We have previously prepared 3,5-dimethyl-1-(2'-quinolyl)-pyrazole (Najib et al., 2012c) and a related Cinchonine derived ligand (Zhang et al., 2011) for the synthesis of photoluminescent zinc (Najib et al., 2012a; Najib et al., 2012b) and iridium complexes (Zhang et al., 2012). These ligands are made by the condensation of the corresponding hydrazine (Najib et al., 2012a) with a β-diketone (Gupta et al., 2007). In our attempted synthesis of 3,5-diphenyl-1-(2'-quinolyl)-pyrazole using the same procedure, we were surprised to prepare the title compound, (I), presumably from initial condensation but only partial dehydration. The reluctance of this benzylic, tertiary alcohol to undergo dehydration may be due to the resulting unfavourable proximity of the phenyl and quinoline groups.

In (I), the pyrazolyl ring has an envelope configuration with the C10 atom being the flap atom. However, the distortion from planarity is relatively minor with the r.m.s. deviation = 0.062 Å and maximum deviations of 0.051 (1) Å for the N1 atom and -0.052 (2) Å for the C10 atom. The N2-bound quinolinyl ring (r.m.s. deviation = 0.009 Å) forms a dihedral angle of 9.90 (7)° with the pyrazolyl plane. The C12-bound phenyl ring is almost co-planar with the pyrazolyl plane [dihedral angle = 8.87 (9)°) whereas the C10-bound phenyl ring forms a dihedral angle of 72.31 (9)°. The latter projects to one side of the pyrazolyl plane and the hydroxy group to the other. The hydroxy group forms an intramolecular hydrogen bond to the quinolinyl-N1 atom, Table 1.

In the crystal packing, C—H···O interactions link molecules into centrosymmetric dimers via 18-membered {···HC₃NCNCO}₂ synthons, Table 1. These are connected into supramolecular layers two molecules thick in the bc plane via C—H···π interactions, Fig. 2 and Table 1. Layers stack along the a axis without specific interactions between them.

Experimental

Ethanol (25 ml) was added to a mixture of 2-hydrazinylquinoline (0.08 g) and dibenzoylmethane (0.23 g) and the resulting solution was refluxed for 48 h. The solvent was removed to obtain an orange residue that was recrystallized from toluene to yield 0.063 g of orange crystals. A second recrystallization from toluene produced 0.035 g (19.1%) of orange crystals. Melting point: 503 K. IR ν/cm^-1: 3409, 3061, 3028, 1616, 1602, 1559, 1507, 1480, 1447, 1432, 1405, 1371, 1343, 1326, 1302, 1263, 1248, 1233, 1170, 1149, 1070, 1050, 856, 828, 756, 698, 692. ¹H NMR 400 MHz (CDCl₃) δ: 8.00 (1H, d), 7.80 (3H, m), 7.58 (3H, m), 7.42 (5H, m), 7.30 (1H, m), 7.21 (2H, m), 7.15(1H, m), 3.83 (1H, d), 3.50 (1H, d), 1.25 (1H, s).