Towards Upcycling Biomass-Derived Crosslinked Polymers with Light

Photodegradable, recyclable, and renewable, crosslinked polymers from bioresources show promise towards developing a sustainable strategy to address the issue of plastics degradability and recyclability. Photo processes are not widely exploited for upcycling polymers in spite of the potential to have spatial and temporal control of the degradation in addition to being a green process. In this report we highlight a methodology in which biomass-derived crosslinked polymers can be programmed to degrade at ≈300 nm with ≈60 % recovery of the monomer. The recovered monomer was recycled back to the crosslinked polymer

β-cyclodextrin as an end-to-end connector

Interaction of β-cyclodextrin (β-CD) with a ditopic molecule having adamantane (AD) at one end and a pyromellitic diimide (PMDI) moiety at the other is studied. The AD moiety undergoes inclusion binding with the β-CD cavity, and the PMDI undergoes binding with the primary rim of β-CD. In an equimolar solution of β -CD and the ditopic molecule in water, β-CD accommodates both modes of complexation simultaneously, leading to the formation of long fibers. The fibers get entangled to give a supramolecular hydrogel with very high water content

β-Cyclodextrin as an End-to-End Connector

Interaction of β-cyclodextrin (β-CD) with a ditopic molecule having adamantane (AD) at one end and a pyromellitic diimide (PMDI) moiety at the other is studied. The AD moiety undergoes inclusion binding with the β-CD cavity, and the PMDI undergoes binding with the primary rim of β-CD. In an equimolar solution of β-CD and the ditopic molecule in water, β-CD accommodates both modes of complexation simultaneously, leading to the formation of long fibers. The fibers get entangled to give a supramolecular hydrogel with very high water content

Study of β-cyclodextrin–pyromellitic diimide complexation. Conformational analysis of binary and ternary complex structures by induced circular dichroism and 2D NMR spectroscopies

Complexation of N-alkyl derivatives of PMDI with β-CD is probed using a variety of techniques. Although MALDI-TOF and CV experiments suggested complex formation, it is very evident from UV–vis and NMR experiments that these complexes are different from regular inclusion complexes. A clear understanding of the structure of the binary complex PMDI@β-CD could be obtained using ICD and NMR ROESY experiments. ICD signals were negative which suggest that the PMDI moiety is placed outside of the cavity. ROESY experiments provide support for this contention. When the alkyl group is t-butyl or 2-propyl, the CH3 protons exist very close to the inner protons of β-CD, but the aromatic proton of PMDI is clearly outside the β-CD cavity. Based on these results we proposed a structure for PMDI@β-CD with the PMDI moiety placed at the narrow rim of β-CD and the N-alkyl group projecting into the cavity and designated these as “rim-binding” complexes. Additional experiments showed that β-CD can accommodate a PMDI moiety at the narrow rim and an adamantane moiety in its cavity simultaneously, resulting in the formation of ternary complexes PMDI⊃β-CD⊂ADA. Structure of the ternary complex was also probed by ROESY. The ternary complex formation can be utilized for the design of higher order functional materials such as CD-based hydrogels

Study of β‑Cyclodextrin–Pyromellitic Diimide Complexation. Conformational Analysis of Binary and Ternary Complex Structures by Induced Circular Dichroism and 2D NMR Spectroscopies

Complexation of <i>N</i>-alkyl derivatives of PMDI with β-CD is probed using a variety of techniques. Although MALDI-TOF and CV experiments suggested complex formation, it is very evident from UV–vis and NMR experiments that these complexes are different from regular inclusion complexes. A clear understanding of the structure of the binary complex PMDI@β-CD could be obtained using ICD and NMR ROESY experiments. ICD signals were negative which suggest that the PMDI moiety is placed outside of the cavity. ROESY experiments provide support for this contention. When the alkyl group is <i>t</i>-butyl or 2-propyl, the CH₃ protons exist very close to the inner protons of β-CD, but the aromatic proton of PMDI is clearly outside the β-CD cavity. Based on these results we proposed a structure for PMDI@β-CD with the PMDI moiety placed at the narrow rim of β-CD and the <i>N</i>-alkyl group projecting into the cavity and designated these as “rim-binding” complexes. Additional experiments showed that β-CD can accommodate a PMDI moiety at the narrow rim and an adamantane moiety in its cavity simultaneously, resulting in the formation of ternary complexes PMDI⊃β-CD⊂ADA. Structure of the ternary complex was also probed by ROESY. The ternary complex formation can be utilized for the design of higher order functional materials such as CD-based hydrogels

Metal-Free Visible Light-Mediated Photocatalysis: Controlling Intramolecular [2 + 2] Photocycloaddition of Enones through Axial Chirality

Atropisomeric enone-imides and enone-amides featuring <i>N</i>-C_Aryl bond rotation were evaluated for intramolecular [2 + 2] photocycloaddition. Straight addition product was observed over cross-addition product with good control over reactivity. The atropselectivity was found to be dependent on the substituent on the aryl ring. Substitution-dependent atropselectivity was rationalized on the basis of a divergent mechanistic pathway

Bionanophotonics: general discussion Faraday Discussions

International audienc

Photocrosslinking between nucleic acids and proteins: general discussion

International audienc

Light induced charge and energy transport in nucleic acids and proteins: general discussion

International audienc