title: Formation of a Syndiotactic Organic Polymer Inside a MOF by a [2+2] Photo-Polymerization Reaction.
abstract: Getting suitable crystals for single-crystal X-ray crystallographic analysis still remains an art. Obtaining single crystals of metal-organic frameworks (MOFs) containing organic polymers poses even greater challenges. Here we demonstrate the formation of a syndiotactic organic polymer ligand inside a MOF by quantitative [2+2] photopolymerization reaction in a single-crystal-to-single-crystal manner. The spacer ligands with trans,trans,trans-conformation in the pillared-layer MOF with guest water molecules in the channels, undergo pedal motion to trans,cis,trans-conformation prior to [2+2] photo-cycloaddition reaction and yield single crystals of MOF containing two-dimensional coordination polymers fused with the organic polymer ligands. We also show that the organic polymer in the single crystals can be depolymerized reversibly by cleaving the cyclobutane rings upon heating. These MOFs also show interesting photoluminescent properties and sensing of small organic molecules.
authors.affiliation: Department of Chemistry and Research Institute of Natural Science, Gyeongsang National University, Jinju 660-701 (Republic of Korea).
authors.forename: In-Hyeok
authors.initials: IH
authors.lastname: Park
authors.affiliation: Department of Chemistry, National University of Singapore, 3, Science Drive 3, Singapore 117543 (Singapore).
authors.forename: Raghavender
authors.initials: R
authors.lastname: Medishetty
authors.affiliation: Department of Chemistry and Research Institute of Natural Science, Gyeongsang National University, Jinju 660-701 (Republic of Korea).
authors.forename: Hyeong-Hwan
authors.initials: HH
authors.lastname: Lee
authors.affiliation: Department of Chemistry, National University of Singapore, 3, Science Drive 3, Singapore 117543 (Singapore).
authors.forename: Caroline Evania
authors.initials: CE
authors.lastname: Mulijanto
authors.affiliation: Department of Chemistry, National University of Singapore, 3, Science Drive 3, Singapore 117543 (Singapore).
authors.forename: Hong Sheng
authors.initials: HS
authors.lastname: Quah
authors.affiliation: Department of Chemistry and Research Institute of Natural Science, Gyeongsang National University, Jinju 660-701 (Republic of Korea). sslee@gnu.ac.kr.
authors.forename: Shim Sung
authors.initials: SS
authors.lastname: Lee
authors.affiliation: Department of Chemistry, National University of Singapore, 3, Science Drive 3, Singapore 117543 (Singapore). chmjjv@nus.edu.sg.
authors.forename: Jagadese J
authors.initials: JJ
authors.lastname: Vittal
keywords: [2+2] cycloaddition; metal-organic frameworks; pedal motion; sensors; syndiotactic polymers