Crystal structure and photoreactivity of a halogen-bonded cocrystal based upon 1,2-diiodoperchlorobenzene and 1,2-bis(pyridin-4-yl)ethylene

Halogen-bonded zigzag molecular network based upon 1,2-diiodoperchlorobenzene and the photoproduct rctt-1,3-bis(pyridin-4-yl)-2,4-diphenylcyclobutane

The formation of a halogen-bonded zigzag mol­ecular network based upon 1,2-di­iodo­perchloro­benzene and the head-to-tail photoproduct rctt −1,3-bis­(pyridin-4-yl)-2,4-di­phenyl­cyclo­butane is reported. The co-crystal is sustained by I⋯N halogen bonds where the photoproduct acts as a linear linker while the donor behaves as a bent two-connected node within the zigzag chain.

The formation and crystal structure of a zigzag mol­ecular network held together by I⋯N halogen bonds is reported. In particular, the halogen-bond donor is 1,2-di­iodo­perchloro­benzene (1,2-C₆I₂Cl₄) while the acceptor is a head-to-tail photoproduct, namely rctt-1,3-bis­(pyridin-4-yl)-2,4-di­phenyl­cyclo­butane (ht-PP). In this co-crystal (1,2-C₆I₂Cl₄)·(ht-PP), the donor acts as a bent two-connected node while the acceptor behaves as a linear linker to form the extended solid. Neighbouring chains pack in a tongue-and-groove-like pattern that engage in various Cl⋯π inter­actions to both the phenyl and pyridyl rings resulting in a supra­molecular two-dimensional sheet.

Halogen-Bond Mediated [2+2] Photodimerizations: À la Carte Access to Unsymmetrical Cyclobutanes in the Solid State

The ditopic halogen-bond (X-bond) donors 1,2-, 1,3-, and 1,4-diiodotetrafluorobenzene (1,2-, 1,3-, and 1,4-di-I-tFb, respectively) form binary cocrystals with the unsymmetrical ditopic X-bond acceptor trans-1-(2-pyridyl)-2-(4-pyridyl)ethylene (2,4-bpe). The components of each cocrystal (1,2-di-I-tFb)·(2,4-bpe), (1,3-di-I-tFb)·(2,4-bpe), and (1,4-di-I-tFb)·(2,4-bpe) assemble via N···I X-bonds. For (1,2-di-I-tFb)·(2,4-bpe) and (1,3-di-I-tFb)·(2,4-bpe), the X-bond donor supports the C=C bonds of 2,4-bpe to undergo a topochemical [2+2] photodimerization in the solid state: UV-irradiation of each solid resulted in stereospecific, regiospecific, and quantitative photodimerization of 2,4-bpe to the corresponding head-to-tail (ht) or head-to-head (hh) cyclobutane photoproduct, respectively.

Iodoperchlorobenzene acts as a dual halogen-bond donor to template a [2 + 2] cycloaddition reaction within an organic co-crystal

The formation of three isostructural co-crystals that utilize iodoperchlorobenzene as a dual halogen-bond donor is reported.