Poly(2‐ethyl‐2‐oxazoline) featuring a central amino moiety

Abstract The incorporation of an amino group into a bifunctional initiator for the cationic ring‐opening polymerization (CROP) is achieved in a two‐step reaction. Detailed kinetic studies using 2‐ethyl‐2‐oxazoline demonstrate the initiators’ eligibility for the CROP yielding well‐defined polymers featuring molar masses of about 2000 g mol –1 . Deprotection of the phthalimide moiety subsequent to polymerization enables the introduction of a cyclooctyne group in central position of the polymer which is further exploited in a strain‐promoted alkyne‐azide click reaction (SpAAC) with a Fmoc‐protected azido lysine representing a commonly used binding motif for site specific polymer–protein/peptide conjugation. In‐depth characterization via electrospray ionization mass spectrometry (ESI) confirms the success of all post polymerization modification steps

Curcuminoid–BF2 complexes: Synthesis, fluorescence and optimization of BF2 group cleavage

Eight difluoroboron complexes of curcumin derivatives carrying alkyne groups containing substituents have been synthesized following an optimised reaction pathway. The complexes were received in yields up to 98% and high purities. Their properties as fluorescent dyes have been investigated. Furthermore, a strategy for the hydrolysis of the BF2 group has been established using aqueous methanol and sodium hydroxide or triethylamine

Responsive glyco-poly(2-oxazoline)s: synthesis, cloud point tuning, and lectin binding

A new sugar-substituted 2-oxazoline monomer was prepared using the copper-catalyzed alkyne-azide cycloaddition (CuAAC) reaction. Its copolymerization with 2-ethyl-2-oxazoline as well as 2-(dec-9-enyl)-2-oxazoline, yielding well-defined copolymers with the possibility to tune the properties by thiol-ene "click" reactions, is described. Extensive solubility studies on the corresponding glycocopolymers demonstrated that the lower critical solution temperature behavior and pH-responsiveness of these copolymers can be adjusted in water and phosphate-buffered saline (PBS) depending on the choice of the thiol. By conjugation of 2,3,4,6-tetra-O-acetyl-1-thio-beta-D-glucopyranose and subsequent deprotection of the sugar moieties, the hydrophilicity of the copolymer could be increased significantly, allowing a cloud-point tuning in the physiological range. Furthermore, the binding capability of the glycosylated copoly(2-oxazoline) to concanavalin A was investigated

The first salen-type ligands derived from 3',5'-diamino-3',5'-dideoxythymidine and -dideoxyxylothymidine and their corresponding copper(II) complexes

BACKGROUND: There are many nucleoside metal complexes known. According to observations made, only very few of them reveal their central ion to be co-ordinated by the sugar part of their molecules. The regio- and stereospecific exchange of the hydroxyl groups at the sugar moiety by chelating units improves its complexation ability and should give access to a new class of chiral ligands. RESULTS: In this paper we present the synthesis of 3',5'-diamino substituted thymidines with ribo- as well as xylo-configuration and the preparation of copper(II) complexes derived from their corresponding Schiff bases. Starting from thymidine, the amino derivatives were prepared in a three and four step reaction sequence respectively. The absolute configuration of the ligands was proved by the three-bond (1)H-(1)H spin spin coupling constants (3)J obtained by NMR-studies. Condensation of the amino derivatives with salicylic aldehydes resulted in the corresponding diimines, which represent a new class of chiral salen-type ligands. All ligands formed uncharged stable copper(II) complexes. The structure of 3',5'-bis(3,5-di-tert-butylsalicylaldiminato)-3',5'-dideoxyxylothymidine-copper(II) could be determined by single crystal X-ray structure analysis. The copper centre in this complex has distorted tetrahedral coordination geometry. CONCLUSION: For the synthesis of 3',5'-diamino-3',5'-dideoxy thymidines with xylo- as well as ribo-configuration an effective synthesis pathway has been developed. Their corresponding salicylidene imines form stable coordination compounds with copper(II) ions. They represent the first salen type complexes of nucleosides with this substitution pattern

Poly(2-oxazoline) glycopolymers with tunable LCST behavior

A series of thermo-responsive glyco-poly(2-oxazoline)s based on 2-ethyl-2-oxazoline and 2-(dec-9-enyl)-2-oxazoline were prepared. To study the effect of the sugar content on the solution behavior in water, two sets of copolymers with constant monomer-to-initiator ratios of 20 and 50 and varying amounts of the hydrophobic alkene functionalized monomer were synthesized. The glycopolymers were obtained by the photoaddition of 2,3,4,6-tetra-O-acetyl-1-thio-beta-D-glycopyranose onto the double bonds followed by deacetylation of the saccharide residues. Turbidimetry measurements of the respective glycopolymers revealed a decreasing cloud point temperature with increasing amount of sugar moieties, proposed to be caused by hydrogen bonding between the sugars and the polymer amide groups, which is enabled by the flexibility of the long decyl spacer. Due to the linear relationship between cloud point temperatures and the sugar content, the cloud points can be easily tailored for specific applications