Design Synthesis And Property Modulation Of Alkenyl Coordination Polymer Stimuli-responsive Materials

Stimuli-responsive materials are receiving more and more attention in the fields of sensors,optoelectronic devices,information storage and artificial intelligence.Coordination polymers have the advantages of inorganic and organic substance.They are an important branch of stimuli-responsive materials with advantages of high stability and easy structure modulation.The[2+2]photocycloaddition reaction is one of the driving factors that induce the stimuli-responsive behavior of the coordination polymer.A series of new coordination polymers have been designed to regulate the stimuli-responsive of crystals at the molecular level using an auxiliary template.1.Four Cd（Ⅱ）coordination polymers（CP₁-CP₄）with similar 1D chain structure were designed and synthesized.The functional groups（-C=C-）in the compound took different arrangements and CP₁-CP₄ showed different stimuli-responsive behavior under[2+2]photocycloaddition.CP₁ with C=C bond aligned in parallel exhibits a violent,reversible bending behavior induced by[2+2]photocycloaddition.CP₄ show the same violent response behavior as CP₁.The CP₂ crystal with lattice solvent（DMAC）underwent desolvation and photodimerization under UV light,which slowed down the reaction speed when desolvation occur,showed weak stimuli-responsive behavior.CP₃ crystal with the C=C bond criss-crossed arrengement does not occur photodimerization and does not show photomechanical behavior under UV light.2.Three Cd（Ⅱ）coordination polymers（CP₅-CP₇）with similar 1D chain motifs were synthesized.The unsaturated bonds-C=C-can be regardd as the photoactive centers in the CPs,which modulates the photostimuli-responsive behavior by precisely regulating the arrangement of the photoactive center.CP₅ with（-C=C-）photoactive center was induced by[2+2]photocycloaddition reaction to split and jump.Replace the photoactive center（-C=C-）of CP₅ with alkyne group（-C≡C-）,no photodimerization occurs in UV light,and does not show photomechanical behavior.CP₇ adds two photoactive centers basis on the CP₅,showing more violent photomechanical behavior than CP₅ under UV light.Moreover,the photoactive centers of CP₇ can be recovered by heat,which can retrigger the photomechanical behaviors.The composite by combining CP_S crystal with PVA can overcome relatively brittleness,low processability,small size and enhance crystal’s practical use.3.Cd（Ⅱ）coordination polymer（CP₈）with 2D structure was designed and synthesized.The pore structure of CP₈ crystal was confirmed by single crystal X-ray diffraction,and the pore structure was active.The adsorption isotherm of N₂ and CO₂ determined that the BET was 11.477 m²/g,the pore volume was 0.094 cm³/g.The framework of the compound was stabilized by XRD after the loss of solvent.The active pore structure was used to design and adsorb different solvents to study the stimuli-responsive behavior of crystals under the modulation of different solvents.Large cracks appear on the surface of CP₈ in the ethanol exchange,and the crystal color darkens.After the methanol exchange of CP₈,cracks invaded the crystal surface faster and the crystal color darkened rapidly.After the exchange of CP₈ with acetonitrile,the crystal has large parallel cracks,accompanied by small cracks,and the crystal color becomes darker.CP₈did not show any stimuli-responsive behavior during acetone exchange.