Chemical Pattern and Photoluminescence On-Off Changes in a Ladder-like MOF via Remarkable Thermal SCSC Transformation

Abstract

We herein report the thermal single-crystal-to-single-crystal (SCSC) transformation of a coordination polymer accompanying molecular level pattern changes and photoluminescence (PL) on-off behavior. Self-assembly of a multitopic olefin-armed NOS2-macrocycle L and silver(I) trifluoroacetate gives rise to an orange emissive ladder-like coordination polymer (ladder-1) in a Λ-V-Λ-V pattern (where “Λ” is a trapezoid and “V” is a reverse trapezoid). Upon heating at 80 °C, surprisingly, ladder-1 undergoes a drastic SCSC transformation to nonemissive ladder-2 with an N-M-N-M pattern (where “N” is a narrow rectangle and “M” is a wide rectangle). A mechanistic pathway for the conversion of ladder-1 to ladder-2 via the bond-breaking/making and pedal motion is proposed. The PL on-off behaviors are discussed based on the structure-property relation. Consequently, the multiple functions of the olefin-armed macrocycle work cooperatively via communications to satisfy the conformational and electronic conditions. This work presents a new perspective on the chemical pattern changes of network materials. © 2024 American Chemical Society.