A Multistimulus Responsive Porous Coordination Polymer: Temperature-Mediated Control of Solid-State [2+2]...

Area of Science:

• Materials Science
• Photochemistry
• Supramolecular Chemistry

Background:

• Porous coordination polymers (PCPs) offer tunable environments for chemical reactions.
• Photochemical [2+2] cycloaddition is a key reaction for forming cyclobutane rings.
• Controlling reaction selectivity in confined spaces remains a challenge.

Purpose of the Study:

• To investigate the selective synthesis of isomeric products via photochemical [2+2] cycloaddition within a PCP.
• To explore the influence of temperature on the reaction outcome.
• To understand the role of ligand flexibility in PCP responsiveness.

Main Methods:

• Synthesis of a porous coordination polymer (PCP) incorporating 1,4-bis[2-(4-pyridyl)ethenyl]-benzene ligands.
• Photochemical [2+2] cycloaddition reactions conducted at different temperatures.
• Analysis of reaction products using spectroscopic and crystallographic techniques.
• Investigation of temperature-induced phase transitions in the PCP.

Main Results:

• Selective formation of two different isomeric cycloaddition products was achieved.
• The specific isomer obtained was directly dependent on the irradiation temperature.
• A rare temperature-induced phase transition was observed, altering ligand conformation.
• This conformational change dictated the regioselectivity of the cycloaddition.

Conclusions:

• The flexibility of ligands in PCPs enables multistimulus responsiveness.
• Temperature can be used as an external stimulus to control photochemical reactions within PCPs.
• This work demonstrates a novel approach for selective synthesis of isomeric compounds using smart materials.