Self-Assembly Of Vinyl Coordination Polymers And Their Solid State [2+2] Photocycloaddition Reactions

Solid state [2+2] photocycloaddition reactions have attracted intensive attention of chemists due to their potential applications in sensor, information storage and post-synthesis, etc. In this thesis, the [2+2] photocycloaddition reactions were investigated by using various analytical methods. Their applications in molecular switch, photoinduced post-synthetic and organic synthesis were also explored. These results were described as following parts:1. A 3D pillar-layer coordination polymer [Ni₃（oba）₂（bpe）₂（SO₄）（H₂O）₄]·H₂O（1） was designed and synthesized. Upon exposure to UV irradiation, compound 1 underwent a single-crystal-to-single-crystal（SCSC） [2+2] photocycloaddition reaction to form [Ni₃（oba）₂（rctt-tpcb）（SO₄）（H₂O）₄]·H₂O（2）. The transformation process was monitored by taking “snapshots” of in situ single crystal X-ray crystallography and 1H NMR spectrum which was proved to follow the first order kinetics. The transformation rate was influenced by several factors including light flux of the UV source, the distances between the sample and the UV source, the heat effect during the irradiation and the dimensions of the cystals. The monitoring technics described herein together with NMR technology offers the opportunity to study the kinetics of other SCSC transformation reactions.2. A 1D coordination polymer of [Zn2（pbda）₂（bpe）₂（H₂O）₂]（3） was designed and synthesized. Compound 3 has a 1D chain structure, during which a pair of bpe ligands from the neighboring chains are arranged in a face-to-face manner. Upon exposure to UV irradiation, compound 3 to underwent a [2+2] photocycloaddition to form a 2D compound [Zn（pbda）（rctt-tpcb）_0.5（H₂O）]（3a）. Compound 3 displayed highly selective sensing toward Fe3+ ion in aqueous solution through fluorescence quenching, which could be used to detect the Fe3+ ion in industrial waste water. Furthermore, compound 3a can selectively adsorb CR over MB, Rh B and MO.3. A 3D compound [Cd（bpa）（bpeb）]₂（4） was synthesized under hydrothermal condition and this process spontaneously resolves into enantiomorphs of 4P and 4M. A chiral induction agent（cyclohexane-1,2-diamine） can lead to the formation of homochiral crystallization of 4P or 4M. Compound 4 underwent highly selective [2+2] photocycloaddition reaction to form [Cd（bpa）（bpvpcbdp）_0.5]₂（5） under UV irradiation. Compound 5 can reform to 4 upon heating or microwave irradiation. The closing and opening cycles result in chiroptical changes,which can be used as chiroptical switch based on photo/microwave stimulation.4. The reaction of Zn SO₄, H₂ oba and S-spy ligands afford complexes 6-8 [Zn（oba）（S-spy）]₂（S-spy）_0.5（4-spy（6）; 4-（2-npy）（7）; 4-npy（8））. A 2D network with hexagnol channels was formed by the linkage of Zn（Ⅱ） and oba2- ligand in compounds 6-8. Olefinic pyridyl ligands are head-to-tail aligned in the hexagnol channels. In 8, the C=C bonds are less than 4.0 ? apart and has a crisscross arrangement. Exposure of 6 and 8 to UV light leads to a [2+2] cycloaddition reaction. Analysis of the “before” and “after” structures of 8 shows a 180o rotation of the naphthyl groups when the photocycloaddition of crisscross C=C bonds is undergone.5. A pseudorotaxane-like coordination network template was assembled by the reaction of Zn SO₄ and H₂ oba ligand. The 1:2 host-guest ternary complexes 9-21 can be easily obtained based on the recognition ability of the coordination template toward different guests. Two guest molecules were located in the pseudorotaxane-like windows and were arranged in a face-to-face fashion to generate the corresponding cyclobutane derivatives after UV irradiation. This work provided a method for synthesis of cyclobutane derivatives based on solid state [2+2] photocycloaddition.