(N 1 E,N 2 E)-N 1,N 2-Bis(4-hexyloxy-3-methoxybenzylidene)ethane-1,2-diamine

The title compound, C30H44N2O4, was obtained from the dimerization of 4-hexyloxyvanillin with ethylenediamine in 95% methanol solution. It adopts a trans configuration with respect to the C=N bond and possesses a crystallographically imposed centre of symmetry.


Comment
The title compound C 30 H 44 N 2 O 4 is a synthetic analogue with a long aliphatic side chain of vanillin. The Schiff base derived from vanillin (Guo et.al, 2008;Li et.al, 2008) exhibit potential antibacterial activity and a potent anti-proliferative effect on a broad spectrum of cancer cell lines (Liang. et.al, 2009;Lim et.al, 2008).
The design of synthetic molecules with self-organised behaviour is one of the fastest growing areas of research. Molecular materials that arise from the self organising properties of the molecules may afford supramolecular architectures (structures beyond the molecule) with chemical and physical properties that may become useful in emerging technologies and medicine (Porta et.al, 2008). Molecules that use non-covalent interactions to self-organise into supramolecular structures have the potential to generate functional materials with a broad range of applications. This unique combination of coordination bond and alkyl interdigitation provide exceptional control over intermolecular interactions and can generate nano scale molecular order as liquid crystalline states and Langmiur-Blodgett films on surfaces.
The crystal adopts a trans configuration with respect to the C=N bond and possesses a crystallographically imposed centre of symmetry.

1) Synthesis of 4-hexyloxy vanillin.
15.215g (0.1 mole) of vanillin was dissolved in 300ml of dimethylformamide in a round-bottom flask. 17.96g (0.13 mole) of potassium carbonate was also added. The resulting mixture was stirred by using a homogeniser maintaining the temperature at 90° C by using an oil bath. 14.03ml (0.1 mole) of bromohexane was added to the reaction mixture through a dropping funnel over a period of 30 minutes (Dholakiya et.al, 2002;Maurya et.al, 2003). The resulting mixture was stirred for 3 hours and cooled to room temperature, diluted with 600ml water. The contents were transferred to a separating funnel extracted with diethyl ether, washed with 5% KOH solution and water respectively. 4-hexyloxy vanillin was obtained and it was recrystallised from hot alcoholic solution.
2) Dimerisation of 4-hexyloxy vanillin with ethylenediamine. 3g (0.05 mole) of ethylenediamine was dissolved in 10ml of ethanol in a round-bottom flask. 23.6g (0.1 mole) of 4hexyloxy vanillin and 5 drops of acetic acid were added into it. It was fitted to a water condenser and heated for 2 hours (Doyle et.al, 2007). It was allowed to cool, washed with methanol and dried in an oven. Recrystallisation of the compound from methanol gave X-ray diffraction quality crystals of the title compound.
supplementary materials sup-2 Refinement All hydrogen atoms were fixed geometrically and allowed to ride on the parent carbon atoms with aromatic C-H = 0.93 Å, aliphatic C-H = 0.98 Å and methyl C-H = 0.96 Å. The displacement parameters were set for phenyl and aliphatic H atoms at U iso (H) = 1.2U eq (C) and for methyl H atoms at U iso (H) = 1.5U eq (C) Figures   Fig. 1. ORTEP of the molecule with atoms represented as 30% probability ellipsoids.