Crystal structures of two different multi-component crystals consisting of 1-(3,4-di-meth-oxy-benz-yl)-6,7-di-meth-oxy-iso-quinoline and fumaric acid.

Two different multi-component crystals consisting of papaverine [1-(3,4-di-meth-oxy-benz-yl)-6,7-di-meth-oxy-iso-quinoline, C(20)H(21)NO(4)] and fumaric acid [C(4)H(4)O(4)] were obtained. Single-crystal X-ray structure analysis revealed that one, C(20)H(21)NO(4)·1.5C(4)H(4)O(4) (I), is a salt co-crystal composed of salt-forming and non-salt-forming mol-ecules, and the other, C(20)H(21)NO(4)·0.5C(4)H(4)O(4) (II), is a salt-co-crystal inter-mediate (i.e., in an inter-mediate state between a salt and a co-crystal). In this study, one state (crystal structure at 100†K) within the salt-co-crystal continuum is defined as the 'inter-mediate'.