Contrast Solid-State Photoreactive Behavior of Two\nTwo-Dimensional Zn(II) Coordination Polymers

Abstract

A two-dimensional photoreactive coordination\npolymer (2D CP), [Zn₂(Fumarate)₂(H₂O)₂(2F-spy)₄] (<b>1</b>) (2F-spy = 2′-fluoro-4-styrylpyridine),\nundergoes partial [2 + 2] cycloaddition reaction under UV light in\na single-crystal-to-single-crystal manner to a three-dimensional (3D)\nCP [Zn₂(Fumarate)₂(H₂O)₂(2F-spy)₃(<i>rctt</i>-2F-ppcb)_0.5] (<b>2</b>) (where <i>rctt</i>-2F-ppcb = 1,3-bis­(4′-pyridyl)-2,4-bis­(2′-fluoro-phenyl)­cyclobutane),\nwhereas another similar photoreactive 2D CP, [Zn₂(Fumarate)₂(3F-spy)₂] (<b>3</b>) (3F-spy = 3′-fluoro-4-styrylpyridine),\nwhen exposed to UV light, forms a cyclobutane ring arising from the\nhetero-cross-coupling of 3F-spy and fumarate, in addition to the expected\ncyclobutane ring, <i>rctt</i>-3F-ppcb (<i>rctt</i>-3F-ppcb = 1,3-bis­(4′-pyridyl)-2,4-bis­(3′-fluoro-phenyl)­cyclobutane)\nby the [2 + 2] cycloaddition reaction of 3F-spy pairs aligned in a\nhead-to-tail (HT) fashion. It is unusual to observe two different\nphotoproducts in a solid-state [2 + 2] photo-cycloaddition reaction\ninvolving CPs. It is possible because the metal ions appear to support\nthe reactions between two different types of ligands.