PHOTOMETRIC PROBE FOR STUDYING SUBSTRATE TETHER SYSTEMS

An aromatic diazonium ion is considered as a reactive probe for determining the ability of a substrate-tether system to isolate adjacent, immobilized species. The immobilized probe molecule can either hydrolyze to the colorless phenol or couple to give a highly colored azo compound. The product distribution depends on whether the substrate-tether system permits interaction of adjacent species. The geometric form (cis vs. trans) of the azo compound which may form is affected by the nature of the substrate and the tether. The cis form is favored over the normally stable trans form when the substrate-tether system holds opposite ends of the doubly immobilized azo molecules together instead of stretching them apart.