Strongly Coupled Porphyrin Arrays Featuring Both π-Cofacial and Linear-π-Conjugative Interactions

A combination of metal-catalyzed cross-coupling and metal-templated cycloaddition reactions have been utilized to establish multiporphyrin compounds 5-(5‘-[15‘,15‘ ‘-bis(10‘ ‘,20‘ ‘-di[4-(3-methoxy-3-methylbutoxy)phenyl]porphinato)zinc(II)]ethyne)-6-[(5‘ ‘‘-10‘ ‘‘,20‘ ‘‘-di[4-(3-methoxy-3-methylbutoxy)phenyl]porphinato)zinc(II)]indane (1) and 5,6-bis(5‘-15‘,15‘ ‘-bis[(10‘,20‘-di[4-(3-methoxy-3-methylbutoxy)phenyl]porphinato)zinc(II)]ethyne)indane (2). Compounds 1 and 2 feature a covalently bridged cofacial bis(porphinato)metal core; ethyne bridging moieties conjugate directly one and two respective peripheral (porphinato)zinc(II) substituents to the macrocyclic framework of their corresponding face-to-face porphyrin units. Optical spectroscopy and electrochemical studies demonstrate substantive electronic interactions between the porphyrin subunits of these compounds. Notably, structural and 1H NMR analyses verify that 1 and 2 possess open conformations necessary for binding small molecules within their respective cofacial (porphinato)metal cores.