The physical properties, including the solid state arrangement,
photophysics, solubility, and electrochemical behavior of a series
of halo-BsubPcs (halo = F, Cl, Br) have been measured (IUPAC name
halo-(7,12:14,19-diimino-21,5-nitrilo-5H-tribenzo(c,h,m)(1,6,11)triazacyclopentadecinato)-boron(III)).
We have found that across the series all are relatively similar in
most regards. Exceptions include that F-BsubPc can be 5 to 25 times
more soluble than Cl-BsubPc in common organic solvents. F-BsubPc was
also found to be hydrolytically stable under the conditions tested,
whereas Cl-BsubPc and Br-BsubPc readily hydrolyzed to form HO-BsubPc.
The relative rates of reaction for the series of halo-BsubPcs under
standard phenoxylation conditions have also been measured. It was
found that F-BsubPc does not undergo phenoxylation, whereas Br-BsubPc
showed a markedly higher reaction rate relative to Cl-BsubPc. Based
on these data some assumptions can be made as to the suitability of
either F-BsubPc or Br-BsubPc to be used in place of the more common
Cl-BsubPc. The data indicate that F-BsubPc is a potential replacement
for Cl-BsubPc in organic electronic materials whereas Br-BsubPc might
be more suitable as a chemical intermediate. Comments on the synthetic
methods used to produce each halo-BsubPc are also made.
We report the synthesis and characterization of a series of boronsubphthalocyanine (BsubPc) dyes which have organic solubility >10 À2 M while being amenable to doping into polymeric films. To achieve high solubility we have placed the 3-pentadecylphenoxy molecular fragment in a variety of positions within the BsubPc chemical structure including around the periphery of the BsubPc ligand and in the axial position to the boron atom. We have found that placement of the 3-pentadecylphenoxy molecular fragment around the periphery adversely affects the photostability of the resulting BsubPc whereas placement in the axial position has little effect. We also confirm that the presence of fluorine atoms around the periphery improves the photostability. Overall we present a systematic study of the 3-pentadecylphenoxy fragment as a solubilizing moiety for BsubPc. The nature of the substituents and their position does not affect the nearly pure magenta color characteristic of BsubPc derivatives.
Reductive amination facilitates the protecting group free post-polymerization functionalisation of a temperature responsive, aldehyde-containing polymer with histidine.
Amino acids are the natural building blocks for the world around us. Highly functional, these small molecules have unique catalytic properties, chirality, and biocompatibility. Imparting these properties to surfaces and other macromolecules is highly sought after and represents a fast-growing field. Polymers functionalized with amino acids in the side chains have tunable optical properties, pH responsiveness, biocompatibility, structure and self-assembly properties. Herein, we review the synthesis of amino acid functional polymers, discuss manipulation of available strategies to achieve the desired responsive materials, and summarize some exciting applications in catalysis, chiral particles, and drug delivery.
The copolymerization of N-isopropylacrylamide (NiPAm) with aldehyde functional monomers facilitates postpolymerization functionalization with amino acids via reductive amination, negating the need for protecting groups. In reductive amination, the imine formed from the condensation reaction between an amine and an aldehyde is reduced to an amine. In this work, we categorize amino acids into four classes based on the functionality of their side chains (acidic, polar neutral, neutral, and basic) and use their amine groups in condensation reactions with aldehyde functional polymers. The dynamic nature of the imine as well as the versatility of reductive amination to functionalize a polymer with a range of amino acids is highlighted. In this manner, amino acid functional polymers are synthesized without the use of protecting groups with high yields, demonstrating the high functional group tolerance of carbonyl condensation chemistry and the subsequent reduction of the imine. Prior to the reduction of the imine bond, transimination reactions are used to demonstrate dynamic polymers that shuffle from a glycine- to a histidine-functional polymer.
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