Synthesis,structures, and ligating ability of 4-tert-butylcalix[n]arene (iso)nicotinoylate

4-tert-Butylcalixn]arenes react with an excess of (iso)nicotinoyl chloride, yielding selectively n-2 acylated products, calixn]-(nico)_n?2(OH)₂, (calix = 4-tert-butylcalixn]arene; n = 4, 6, and 8; nico = (iso)nicotinoylate) of alternate conformations. Their structures were determined by X-ray single crystallography and NMR spectra. The UV–vis spectra indicated that a new absorption band of the complexes appears upon the addition of cobalt(II) dichloride, and its crystal structure was resolved.