Polyladderane Constructed from a Gemini Monomer through Photoreaction

Abstract

Polyladderane, the first polymer to contain the ladderane functional group, was synthesized from a gemini monomer through photoreaction in the solid state. The modular design of the gemini monomers used to create polyladderane allowed specific structural modification, resulting in the formation of two distinct polymer products. Monomers were synthesized by connecting two photoreactive units, either sorbic acids (monomer I) or 2-furanacrylic acids (monomer II), with a 1,4-butanediol linker. Single-crystal X-ray diffraction analysis of the monomers confirmed that they packed in the desired head-to-tail orientation and within a viable distance for photoreaction by electronically complementary interaction. Pre-organized gemini monomers were irradiated with UV light and monitored by FT-IR. Two polyladderanes with cis,anti,cis-[3]-ladderane as a characteristic functional group were constructed stereospecifically in 24-36 hours.

Size Matters: [2 + 2] Photoreactivity In Macro- and Microcrystalline Salts of 4-Aminocinnamic Acid

“…Incomplete photoconversion was confirmed also by FTIR spectroscopy, as evidenced by residual peaks at 980 (C–H CC out-of-plane bending), 1640 (CC stretching), and 1700 cm –1 (conjugated CO stretching) present in the irradiated sample (see Figure SI-3); − , a shoulder at 1725 cm –1 , due to the partial deconjugation of the carbonyl group, can also be detected in the spectrum.…”

Renewable Cyclobutane-1,3-dicarboxylic Acid (CBDA) Building Block Synthesized from Furfural via Photocyclization

“…It seems that the intermolecular hydrogen bonds in the solid state disrupt the weak complementary π−π stacking between adjacent acid molecules that could lead to the formation of the α-form crystal., 73−75 might offer the desired α-form packing in the solid state because the strong intermolecular hydrogen bonds between the carboxylic acid groups are removed. 15,65,76,77 To evaluate the feasibility of this hypothesis, we prepared an ethyl ester of 2-furanacrylic acid, which turned out to be a liquid at room temperature. 78−80 Low-temperature solvent-free crystallization was applied to prepare a crystalline solid of ethyl furanacrylate (3) at −20 °C.…”

“…Just as with furfural, malonic acid is a bioadvantaged chemical, meaning petrochemical processes cannot compete with biochemical production. − The subsequent decarboxylation of the Knoevenagel adduct in the same pot gave 2-furanacrylic acid ( 2 ) in 87% isolated yield. , Our previous study showed that 2 can be dimerized directly through photocycloaddition in the solid state to give CBDA-2 (head-to-head dimer), and all other related reports have also suggested that the β-form crystal (head-to-head packing) is the preferred packing conformation of 2 . ,, As such, despite its great potential applications in materials, the cyclobutane-1,3-diacid (head-to-tail dimer of 2 , CBDA-5, shown in Scheme ) has never been reported before, as it would need to arise from the α-form crystal (head-to-tail packing) of 2 . It seems that the intermolecular hydrogen bonds in the solid state disrupt the weak complementary π–π stacking between adjacent acid molecules that could lead to the formation of the α-form crystal., − Thus, we hypothesized that ethyl 2-furancarylate might offer the desired α-form packing in the solid state because the strong intermolecular hydrogen bonds between the carboxylic acid groups are removed. ,,, …”

“…To explore the potential application of this novel building block, a linear, fully biobased polymer prototype has been synthesized from CBDA-5. This polyester represents an example of the emerging cyclobutane-containing polymers (CBPs). ,,− …”

Furfural-Derived Diacid Prepared by Photoreaction for Sustainable Materials Synthesis

“…The parallel CC double bonds and a distance of 3.73 Å between them in the FAA crystal make it a good candidate for [2 + 2] photosynthesis (Figure ). ,,,− Our group applied blacklight UV irradiation to the FAA crystalline powder in a slurry reaction to synthesize this diacid building block stereospecifically in 95% isolated yield within 12 h. Only one of the six stereoisomers of the head-to-head dimers was generated (SI) because a solid-state photoreaction normally proceeds by the pathway with the smallest movement of atoms. The photoproduct CBDA-2 , cis -3,4-di­(furan-2-yl)­cyclobutane-1,2-dicarboxylic acid, was fully characterized by several different methods including NMR spectra (SI Figure 3.1).…”