2-[(Naphthalen-1-yl­methyl­idene)amino]-5-methyl­phenol

Gabriella Orona; Vanessa Molinar; Frank R Fronczek; Ralph Isovitsch

doi:10.1107/S1600536811034556

. 2011 Aug 27;67(Pt 9):o2505–o2506. doi: 10.1107/S1600536811034556

2-[(Naphthalen-1-ylmethylidene)amino]-5-methylphenol

Gabriella Orona ^a, Vanessa Molinar ^b, Frank R Fronczek ^c, Ralph Isovitsch ^d,^*

PMCID: PMC3200862 PMID: 22059051

Abstract

The title compound, C₁₈H₁₅NO, is a Schiff base prepared from an acid-catalyzed condensation reaction between 1-naphthaldehyde and 6-amino-m-cresol. Intramolecular hydrogen bonding occurs via an O—H⋯N interaction, generating an S(5) ring motif. Neighboring phenol groups participate in intermolecular hydrogen bonding through an O—H⋯O interaction, forming chains. The O atom of the phenol group also participates in an intermolecular C—H⋯O interaction with an H atom of one of the naphthalene rings. The C—N=C—C torsion angle between the phenol and naphthalene rings is −179.8 (2)°. Crystal packing involves stacks with the molecules interacting through the π-systems of the C=N with both the phenol system and one of the naphthalene rings.

Related literature

For related structures, see: De et al. (2008 ▶); Villalpando et al. (2010 ▶); Yildz et al. (2005 ▶). For bond-length data, see Allen et al. (1987 ▶). For background to the synthesis of Schiff bases, see: Borisova et al. (2007 ▶). For background to the use of Schiff bases in solar energy collection, see: Mak et al. (2009 ▶). For background to the intermolecular interactions of π-systems, see: Jennings et al. (2006 ▶); Zhang et al. (2006 ▶). For a description of hydrogen-bonding motifs, see: Bernstein et al. (1995 ▶).

Experimental

Crystal data

C₁₈H₁₅NO
M _r = 261.31
Orthorhombic,
a = 4.8246 (10) Å
b = 9.766 (2) Å
c = 28.024 (7) Å
V = 1320.4 (5) Å³
Z = 4
Mo Kα radiation
μ = 0.08 mm⁻¹
T = 90 K
0.25 × 0.17 × 0.10 mm

Data collection

Nonius KappaCCD (with an Oxford Cryosystems Cryostream cooler) diffractometer
14676 measured reflections
1552 independent reflections
1169 reflections with I > 2σ(I)
R _int = 0.034

Refinement

R[F ² > 2σ(F ²)] = 0.041
wR(F ²) = 0.090
S = 1.05
1552 reflections
185 parameters
H atoms treated by a mixture of independent and constrained refinement
Δρ_max = 0.19 e Å⁻³
Δρ_min = −0.17 e Å⁻³

Data collection: COLLECT (Nonius 2000 ▶); cell refinement: DENZO and SCALEPACK (Otwinowski & Minor, 1997 ▶); data reduction: DENZO and SCALEPACK; program(s) used to solve structure: SIR97 (Altomare et al., 1999 ▶); program(s) used to refine structure: SHELXL97 (Sheldrick, 2008 ▶); molecular graphics: ORTEP-3 for Windows (Farrugia, 1997 ▶); software used to prepare material for publication: SHELXL97.

Supplementary Material

Crystal structure: contains datablock(s) I, global. DOI: 10.1107/S1600536811034556/lr2024sup1.cif

e-67-o2505-sup1.cif^{(18KB, cif)}

Structure factors: contains datablock(s) I. DOI: 10.1107/S1600536811034556/lr2024Isup2.hkl

e-67-o2505-Isup2.hkl^{(76.5KB, hkl)}

Supplementary material file. DOI: 10.1107/S1600536811034556/lr2024Isup3.cml

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

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

D—H⋯A	D—H	H⋯A	D⋯A	D—H⋯A
O1—H1O⋯O1ⁱ	0.87 (3)	2.17 (3)	2.916 (2)	143 (2)
O1—H1O⋯N1	0.87 (3)	2.24 (3)	2.701 (3)	113 (2)
C2—H2⋯O1ⁱ	0.95	2.53	3.382 (3)	150
C18—H18C⋯Cgⁱⁱ	0.98	2.57	3.504 (3)	160

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

Acknowledgments

Whittier College is acknowledged for the funds that supported this research. The purchase of the diffractometer was made possible by grant No. LEQSF(1999–2000)-ENH-TR-13, administered by the Louisiana Board of Regents.

supplementary crystallographic information

Comment

Schiff bases are traditionally prepared via an acid-catalyzed condensation reaction between an aniline derivative and a ketone or aldehyde (Borisova et al., 2007). Our research examines the photophysics of polycyclic aromatic hydrocarbon Schiff bases and their metal complexes toward the goal of applying them to solar energy collection (Mak et al., 2009).

The structure of the title compound is shown in Figure 1. The atoms of the central double bond (N1—C11) have a bond length and bond angles that indicate their sp² hybrid character (Allen et al., 1987). For example, N1—C11 has a length of 1.273 (3) Å. Angles about the N1—C11 double bond, C11—N1—C12 and N1—C11—C1, are 121.1 (2) and 122.5 (2)° respectively. The molecule deviates sligthly from planarity with C12—N1—C11—C1 torsion angle of -179.8 (2)° Other observed bond angles and lengths correspond well with those of similar phenolic Schiff bases. (De et al. , 2008; Villalpando et al., 2010).

Intramolecular hydrogen bonding was observed in the title compound in an O—H···N (O1H—N1) interaction with a H···N distance of approximately 2.2 Å and a O···N distance of 2.701 (2) Å, generating S(5) ring motifs. Neighboring OH (O1H) groups participated in intermolecular hydrogen bonding through an O—H···O (at x - 1/2, 1/2 - y, 1 - z) interaction with an H···O distance of approximately 2.2 Å and an O···O distance of 2.916 (2) Å, with an O—H···O bond angle of 143 (2)°. This type of intra- and intermolecular hydrogen bonding has been observed in other Schiff bases (Yildz et al., 2005; Villalpando et al., 2010).

Crystals of the title compound were composed of stacks of the molecule engaged in various intermolecular π-interactions. A π-π interaction occurred through the central double bond (N1—C11) and one of the naphthalene rings (C1—C2—C3—C4—C10—C9) with a N···Cg (at x + 1, y, z) distance of 3.336 (2) Å. Another π-π interaction occurred through the central double bond (N1—C11) and the phenol ring (C12—C17) with a N···Cg (at x - 1, y, z) distance of 3.491 (2) Å. A C—H···π interaction was observed between the methyl hydrogen atoms (C18—H) and the phenol ring (C12—C17) with a H···Cg (at x + 1, y, z) distance of approximately 2.6 Å and a C18···Cg distance of 3.504 (2) Å, with a C18—H···Cg angle of 160°.

Stacks of the molecule interacted in two ways. The first being the intermolecular O—H···O hydrogen bonding described above. The second being a C—H···O (C2H—O1) interaction with a H···O (at x - 1/2, 1/2 - y, 1 - z) distance of approximately 2.5 Å and a C···O distance of 3.382 (3) Å with a C—H···O bond angle of 150°. These types of interactions have been seen in other aromatic systems (Jennings et al., 2006; Zhang et al., 2006).

Experimental

Synthetic procedures were carried out using standard techniques. Solvents and reagents were purchased from Sigma-Aldrich or Acros Organics and used as received. The melting point was determined in an open capillary and is uncorrected. The ¹H-NMR spectrum was recorded on a Jeol ECX 300 MHz s pectrometer using TMS as the internal standard. The IR spectrum was recorded as a KBr disk on a JASCO 460 F T—IR.

In a 25 ml roundbottom flask, 1-napthaldehyde (8.7 ml, 0.64 mmol) was added to 6-amino-m-cresol (0.087 g, 0.70 mmol) along with four drops of concentrated acetic acid and 10 ml me thanol. The solution was refluxed for 2 h. When the reaction time was complete, the reaction volume was reduced by half and allowed to cool slowly. The resultant dark orange crystals were vacuum filtered and air dried. 0.102 g of product were obtained, which is a 61% yield.

MP: 111–113°C. IR (KBr): 3053, 1696, 1510 cm^{-1. 1}H NMR (300 MHz, CDCl₃) 9.38 (s, 1 H), 8.85 (d, 1 H), 8.17 (d, 1 H), 7.97 (m, 2 H), 7.61 (m, 3 H), 7.29 (m, 2 H), 6.89 (d, 1 H), 6.77 (m, 1 H), 2.37 (s, 3 H) p.p.m.. EI—GC—MS: m/z= 261.1. TLC (silica, CH₂Cl₂): R_f= 0.77.