Indirect photopatterning of functionalized organic monolayers via copper-catalyzed "click chemistry"

Antioxidant and Antibacterial Activities of Dodecyl Tannin Derivative Linked with 1,2,3-Triazole

Dodecyl tannin derivative linked with 1,2,3-triazole was prepared by the click reaction of dodecyl azide and alkynylated tannin. The structure of tannin derivative was identified by FT-IR spectrometer and elemental analyzer, and the surface activity, antioxidant activity and antimicrobial activity of tannin derivative were studied. The surface tension of tannin derivative was significantly reduced because of the introduction of long chain alkyl groups, and the lowest surface tension was 38.87 mN/m at 1.0 mg/mL. The tannin derivative had strong ability to scavenge 1,1-diphenyl-2-picrylhydrazyl radical, the scavenging rate could reach 89.08 % at 0.25 mg/mL. The tannin derivative exhibited strong antibacterial activity against E. coli and S. aureus due to the increased fat-solubility of tannin derivative and the introduction of antibacterial triazole groups in molecular structure of tannin derivative, and the bacteriostatic ratios of tannin derivative against E. coli and S. aureus were 92.16 % and 89.21 % at 2.0 mg/mL, respectively. The tannin derivative can be used as good candidates for antibacterial packaging or antioxidant supplements.

Light-Triggered Click Chemistry

The merging of click chemistry with discrete photochemical processes has led to the creation of a new class of click reactions, collectively known as photoclick chemistry. These light-triggered click reactions allow the synthesis of diverse organic structures in a rapid and precise manner under mild conditions. Because light offers unparalleled spatiotemporal control over the generation of the reactive intermediates, photoclick chemistry has become an indispensable tool for a wide range of spatially addressable applications including surface functionalization, polymer conjugation and cross-linking, and biomolecular labeling in the native cellular environment. Over the past decade, a growing number of photoclick reactions have been developed, especially those based on the 1,3-dipolar cycloadditions and Diels-Alder reactions owing to their excellent reaction kinetics, selectivity, and biocompatibility. This review summarizes the recent advances in the development of photoclick reactions and their applications in chemical biology and materials science. A particular emphasis is placed on the historical contexts and mechanistic insights into each of the selected reactions. The in-depth discussion presented here should stimulate further development of the field, including the design of new photoactivation modalities, the continuous expansion of λ-orthogonal tandem photoclick chemistry, and the innovative use of these unique tools in bioconjugation and nanomaterial synthesis.

One-component rapid Norrish Type II photoinitiation of bulk photo-CuAAC polymer networks

A one-component photoinitiation scheme was devised utilizing amine-centered trialkyne monomers for the formation of bulk photo-CuAAC polymer networks. The novel monomers maintain rapid polymerization kinetics and allow for tuning of the T_g.

Effect of Chemical Microenvironment in Spirothiopyran Monolayer Direct-Write Photoresists

We study the effect of the microenvironment on writing chemical patterns into spirothiopyran monolayers over large areas in a single step with light. Surfaces functionalized with photoresponsive spirothiopyran are fabricated by chemically modifying amine-terminated monolayers. The merocyanine isomer selectively participates in a thiol-Michael addition reaction with maleimide-functionalized molecules, rendering these surfaces ideal for fast, mask-less direct writing. The local microenvironment of spirothiopyran is found to strongly influence the kinetics of photoswitching. The quantum yield of ring opening is found to be 17 times faster for spirothiopyran surrounded by a locally charged environment rich in guanidinium diluent molecules as compared to a closed-packed monolayer without diluents. Hydrophilic environments are also found to improve the kinetics of ring closing. Optimization of the diluent concentration leads to dramatic improvements in both contrast and yield of direct writing. This enables the monolayer to be used for maskless two-color photopatterning in which spatial control over patterning is obtained by varying the relative intensity of incident UV and green light. These experiments demonstrate the capacity of spirothiopyran monolayers to serve as a versatile toolbox for rapid, large-area surface functionalization.