Synthesis and properties of carborane-functionalized aliphatic polyester dendrimers.
The incorporation of multiple p-carborane cages within an aliphatic polyester dendrimer was accomplished through the preparation of a bifunctional carborane synthon. A p-carborane derivative having an acid and a protected alcohol functionality was found to efficiently couple to peripheral hydroxyl groups of low-generation dendrimers under standard esterification conditions. Deprotection of carborane hydroxyl groups allowed for further dendronization through a divergent approach using the highly reactive anhydride of benzylidene-protected 2,2-bis(hydroxymethyl)propanoic acid. This approach was used to prepare fourth- and fifth-generation dendrimers that contain 4, 8, and 16 carborane cages within their interior. Upon peripheral deprotection to liberate a polyhydroxylated dendrimer exterior, these structures exhibited aqueous solubility as long as a minimum of eight hydroxyl groups per carborane were present. Several of the water-soluble structures were found to exhibit a lower critical solution temperature. Additionally, irradiation of these materials with thermal neutrons resulted in emission of gamma radiation that is indicative of boron neutron capture events occurring within the carborane-containing dendrimers.
Parrott
Matthew C
MC
Department of Chemistry, McMaster University, Hamilton, Ontario, Canada.
Marchington
Erin B
EB
Valliant
John F
JF
Adronov
Alex
A
D000143:Acids / Q000737:chemistry; D000438:Alcohols / Q000737:chemistry; D001597:Benzylidene Compounds / Q000737:chemistry; D001880:Boranes / Q000138:chemical synthesis*; D016754:Boron Neutron Capture Therapy / Q000379:methods; D005720:Gamma Rays; D006880:Hydroxy Acids; D046911:Macromolecular Substances / Q000138:chemical synthesis*; D009682:Magnetic Resonance Spectroscopy; D009942:Organometallic Compounds / Q000138:chemical synthesis*; D011091:Polyesters / Q000737:chemistry*; D011422:Propionates / Q000737:chemistry; D012995:Solubility; D013329:Structure-Activity Relationship; D013696:Temperature; D014867:Water / Q000737:chemistry
D000143:Acids; D000438:Alcohols; D001597:Benzylidene Compounds; D001880:Boranes; D006880:Hydroxy Acids; D046911:Macromolecular Substances; D009942:Organometallic Compounds; D011091:Polyesters; D011422:Propionates; D014867:Water; C110034:2,2-bis(hydroxymethyl)-propionic acid