Closed-loop circular utilization of plastics is of manifold significance, yet energy-intensive and poorly selective scission of the ubiquitous carbon–carbon (C–C) bonds in contemporary commercial polymers pose tremendous challenges to envisioned recycling and upcycling scenarios. Here, we demonstrate a topochemical approach for creating elongated C–C bonds with a bond length of 1.57∼1.63 Å between repeating units in the solid state with decreased bond dissociation energies. Elongated bonds were introduced between the repeating units of 12 distinct polymers from three classes. In all cases, the materials exhibit rapid depolymerization via breakage of the elongated bond within a desirable temperature range (140∼260 °C) while otherwise remaining remarkably stable under harsh conditions. Furthermore, the topochemically prepared polymers are processable and 3D-printable while maintaining a high depolymerization yield and tunable mechanical properties. These results suggest that the crystalline polymers synthesized from simple photochemistry and without expensive catalysts are promising for practical applications with complete materials’ circularity.

Three new isostructural 3D lanthanide metal-organic frameworks (Ln-MOFs), {H[LnL(H 2 O)]·2 H 2 O} n (1-Ln) (Ln = Eu 3 + ,G d 3 + and Tb 3 + ), based on infinite lanthanide-carboxylate chains were constructed by employing an etherseparated 5,5'-oxydiisophthalic acid (H 4 L) ligand under solvothermal reaction. 1-Eu and 1-Tb exhibit strong red and green emission, respectively,t hrough the antenna effect, as demonstrated through ac ombinationo fc alculation and ex-perimental results. Moreover,aseries of dichromatic doped 1-Eu x Tb y MOFs were fabricated by introducing different concentrationso fE u 3 + and Tb 3 + ions, and they displaya nu nusual variation of luminescent colors from green, yellow, orange to red. 1-Eu with channels decorated by ether O atoms andt he open metal sites displays good performance for CO 2 capturea nd conversion between CO 2 and epoxides into cyclic carbonates. Figure 1. Structure of 5,5'-oxydiisophthalic acid (H 4 L).[a] Dr.

A selenophene-containing conjugated organic ligand 2-(4'-methyl-5'-(5-(3-methylthiophen-2-yl)selenophen-2-yl)-[2,2'-bithiophen]-5-yl)ethan-1-aminium (STm) is synthesized and incorporated into Sn(II)-based two-dimensional perovskites, (STm)2SnI4. By introducing the STm ligand, the band offset between perovskite and ligand can be...

Topochemical polymerizations hold the promise of producing high molecular weight and stereoregular single crystalline polymers by first aligning monomers before polymerization. However, monomer modifications often alter the crystal packing and result in non-reactive polymorphs. Here, we report a systematic study on the side chain functionalization of the bis(indandione) derivative system that can be polymerized under visible light. Precisely engineered side chains help organize the monomer crystals in a one-dimensional fashion to maintain the topochemical reactivity. By optimizing the side chain length and end group of monomers, the elastic modulus of the resulting polymer single crystals can also be greatly enhanced. Lastly, using ultrasonication, insoluble polymer single crystals can be processed into free-standing and robust polymer thin films. This work provides new insights on the molecular design of topochemical reactions and paves the way for future applications of this fascinating family of materials.