CO2‐Breathing Induced Reversible Activation of Mechanophore within Microgels

In this work, CO₂‐breathing induced reversible activation of mechanophore within microgels is reported. The microgels are prepared through soap‐free emulsion polymerization of CO₂‐switchable monomer 2‐(diethylamino)ethyl‐methacrylate, using spiropyran (SP) based mechanophore MA‐SP‐MA as cross‐linker. The microgels can be swollen by CO₂ aeration. The swelling of microgels activates the SP mechanophore into merocyanine, causing distinguished color and fluorescence change. Moreover, these transitions are highly reversible, and the initial states of microgels can be easily recovered by “washing off” CO₂ with N₂. The present contribution represents the first example of CO₂‐breathing activation of mechanophore within microgels.

     

Comparative study of reductive amination reaction on 5-(4-formyl-3,5-dimethoxyphenoxy)valeric acid and its monomethoxy analog using the Multipin™ approach

The 5-(4-formyl-3,5-dimethoxyphenoxy)valeric acid (Barany)linker and its monomethoxy analog were applied to theMultipin method of solid phase synthesis. Acomparative assessment of reductive amination and cleavage ofthese linkers under conditions of multiple synthesis indicatedthat both were applicable to a broad range of primary aminesincluding aniline and 4-nitroaniline. Apart from the greaterlability of the dimethoxy version under TFA cleavage, there wasno observable advantage of one linker over the other within thedescribed experiment.     

1H and 13C spectral assignment of symmetrical bis[(4-aminosubstituted)quinolinium] derivatives

1H and 13C NMR spectroscopic data of both the quinolinium ring and the spacers for 32 symmetrical bisquinolinium compounds were assigned by a combination of one- and two-dimensional experiments (DEPT, HMBC, HMQC). The compounds have electron-releasing groups at position 4 of the quinolinium ring, with several arylalkyl linkers such as the 3,3'-, 4,4'-bis(methylene)biphenyl and 4,4'-bis(methylene)bibenzyl moieties.     

Cell‐Permeant and Photocleavable Chemical Inducer of Dimerization

Chemical inducers of dimerization (CIDs) have been developed to orchestrate protein dimerization and translocation. Here we present a novel photocleavable HaloTag‐ and SNAP‐tag‐reactive CID (MeNV‐HaXS) with excellent selectivity and intracellular reactivity. Excitation at 360 nm cleaves the methyl‐6‐nitroveratryl core of MeNV‐HaXS. MeNV‐HaXS covalently links HaloTag‐ and SNAP‐tag fusion proteins, and enables targeting of selected membranes and intracellular organelles. MeNV‐HaXS‐mediated translocation has been validated for plasma membrane, late endosomes, lysosomes, Golgi, mitochondria, and the actin cytoskeleton. Photocleavage of MeNV‐HaXS liberates target proteins and provides access to optical manipulation of protein relocation with high spatiotemporal and subcellular precision. MeNV‐HaXS supports kinetic studies of protein dynamics and the manipulation of subcellular enzyme activities, which is exemplified for Golgi‐targeted cargo and the assessment of nuclear import kinetics.     

Six new photolabile linkers for solid-phase synthesis. 1. Methods of preparation

In the synthesis of combinatorial chemical libraries on solid phase, there is a need to cleave the compounds from the solid support before the library can be tested for biological activity. It is advantageous to use linkers which will release the libraries by mild photolytic cleavage. We have developed six new linkers of the photosensitive α-methyl 2-nitrobenzyl type containing amino, hydroxy, bromo and methylamino groups, and also 4-nitrophenoxycarbonyl activated OH and NH₂ groups. This revised version was published online in August 2006 with corrections to the Cover Date.