Photoresponsive and Redox-Active Supramolecular Systems with Rigid Sp Carbon Chain Spacers

Abstract

The construction and investigation of photoresponsive and redox-active supramolecular systems with acetylenyl (polyyne) and cumulenic sp hybridized carbon chains (C_n) are reported here. Novel types of one-dimensional rigid molecular rods and macrocyclic molecular squares with controllable and yet fixed chain lengths or cavity sizes are explored. Such systems will have the desired features such as synthetic accessibility, coordination versatility, rigidity, directionality, photostability, electronic conductivity, controllable distances between donors and acceptors, and controllable cavity sizes in macrocyclic molecular squares. These features are extremely important to the future applications of these new rigid supramolecular systems in molecular photonic and electronic devices, light-energy conversion, molecular recognition, and host-guest chemistry.

In addition to the exploration of synthetic features, the solution state redox characteristics and molecular photophysics of the metal-containing supramolecular systems with sp carbon chains are also under investigation. This includes the modulation of electronic communication between multiple redox centers spanned by rigid spacers of various chain lengths and the study of long-range, directional photoinduced energy/electron transfer across such spacers. In addition, covalent surface confinement of systems containing sp carbon chains is also investigated here. Specifically, UV/vis and X-ray photoelectron spectroscopy have been used as spectroscopic tools to monitor the growth of mono-and multilayer thin films.

Key Words:

• Rigid supramolecules
• rigid-rod molecules
• macrocyclic molecular squares
• cumulenic and acetylenyl (polyyne) sp carbon chains
• phosphines
• metal complexes
• electron/energy transfer
• electronic communication
• steady-state and time-resolved emission
• transient absorption spectroscopy
• thin films
• covalent surface modification
• X-ray photoelectron spectroscopy