Abstract
The findings of the first reported guest centric encapsulation study are presented within. The guests were of interest as petrol and diesel (fuel) additives, with the focus on 2-ethylhexyl nitrate (2-EHN), di-tert-butyl peroxide (DTBP), aniline, N-methylaniline (NMA) and N,N-dimethylaniline (NNDMA). Complexation with 2-EHN and DTBP was achieved with the novel calix[4]arene derivative, 5,11,17,23-tetra-tert-butyl, 25 27-bis(oxyethylphenylurea), 26,28-dihydroxycalix[4]arene, CA(III). This was confirmed in solution by the use of NMR techniques. The multi-step procedure to yield a tetrol cavitand, with recent updates to the procedures are fully described. A new carceplex system with aniline encapsulated, carceplex aniline (4,24-5,5'-6,10-11,11’-12,16-17,17’-18,22-23,23’-4’,24’-6’,10’-12’,16’-18',22'-dodecamethylenedioxy, 2,8,14,20,2’,8’,14’,20’-octapentyl-bis-calix[4]arene aniline) was produced in a pioneering pressure tube encapsulation following unsuccessful attempts under reflux conditions. A pyrogallol[4]arene with pentyl pendant group (2,8,14,20-tetrapentylpyrogallol[4]arene) PA(I) was synthesised and successfully employed for self-assembled complex formation with aniline, NMA and NNDMA. These complexes were found to be stable in polar and apolar media at 313 K over a duration of 2 months. The complexes were of stoichiometry 10:1 (aniline : PA(I)), 12:1 (NMA:PA(I)), and 4:1 (NNDMA:PA(I)). Significant variation was observed when complexes were analysed by TGA in air up to 800°C compared to control. PA(I) aniline and PA(I) NMA displayed solubilities in apolar media making them suitable for analysis in test engines as fuel additives. The first report of a (two-step) carcerand synthesised from pyrogallol[4]arene, PA(I) with the introduction of methylene dioxy spanning and bridging groups, yielding the novel carcerand 4,24-5,4’-6,5’-10,11’-12,16-17,16’-18,17’-22,23’-23,24’-6,10’-18’,22’-dodecamethylenedioxy, 2,8,14,20,2’,8’,14’,20’-octapentyl-bis-calix[4]arene is also presented.