The synthesis of two 1,3-bis(4-ethynylbenzyloxy)calix[4]arenes, 5,11,17,23-tetrakis(1,1-dimethylethyl)-25,27-bis(4-ethynylbenzyloxy)-26, 28-dihydroxycalix[4]arene (1) and 25,27-bis(4-ethynylbenzyloxy)-26,28-dihydroxycalix[4]arene (2), was accomplished through Sonogashira coupling of appropriate calixarene derivatives. Methods for the polymerization of these bifunctional building blocks with Rh(I) as a catalyst, leading ultimately to conjugated polymers having calix[4]arene units incorporated into the main chain, were explored. Calixarenes 1 and 2 were efficiently polymerized with rhodium-based initiators and afforded the conjugated polymers poly{5,11,17,23-tetrakis(1,1-dimethylethyl)-25,27-bis(4-ethynylbenzyloxy )-26,28-dihydroxycalix[4]arene} (poly 1) and poly{25,27-bis(4-ethynylbenzyloxy)-26,28-dihydroxycalix[4]arene}. Depending on the conditions, high conversions and good yields were obtained. The effects of adding cocatalysts (NHEt2 and/or PPh3) were studied in connection with the number-average molecular weight and the molecular weight distribution of the resultant polymer (poly 1) and tentatively correlated with the formation of low-molecular-weight materials. A catalytic system containing triphenylphosphine as the sole additive ([Rh(nbd)Cl](2); [Rhl/[PPh3] = 0.5) proved to be the best for the polymerization of p-tert-butylcalixarene compound 1. Linear polymers having high number-average molecular weights (up to 1.1 X 10(5) g mol(-1)) With low polydispersities were produced under these conditions. For debutylated homologue 2, its polymerization was best carried out in the absence of any added cocatalyst. A cyclopolymerization route, comprising the intramolecular ring closing of the calix[4]arene pendant ethynyl groups followed by an intermolecular propagation step, is advanced to explain the results. (c) 2006 Wiley Periodicals, Inc.