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

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.

The title compound, C 18 H 15 NO, 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-HÁ Á ÁN interaction, generating an S(5) ring motif. Neighboring phenol groups participate in intermolecular hydrogen bonding through an O-HÁ Á ÁO interaction, forming chains. The O atom of the phenol group also participates in an intermolecular C-HÁ Á ÁO 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 À179.8 (2) . Crystal packing involves stacks with the molecules interacting through the -systems of the C N with both the phenol system and one of the naphthalene rings.
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. 2-[(Naphthalen-1-ylmethylidene)amino]-5-methylphenol G. Orona, V. Molinar, F. R. Fronczek and R. Isovitsch 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 sp 2 hybrid character (Allen et al., 1987). For example, N1-C11 has a length of 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 1 H-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.

Refinement
All H atoms on C were placed in calculated positions, guided by difference maps, with C-H bond distances 0.95-0.98 Å, and thereafter refined as riding. A torsional parameter was refined for the Me group. The hydroxy H atom coordinates were refined. Isotropic displacement parameters for H were assigned as U iso =1.2U eq , (1.5 for methyl and OH). Friedel pairs were averaged. Fig. 1. ORTEP plot of the title compound with displacement ellipsoids at the 50% probability level. H atoms are shown with arbitrary radius.