Twelvefold Functionalization of an Icosahedral Surface by Total Esterification of [B12(OH)12]2−: 12(12)-Closomers

Abstract

Esterified B12 icosahedra with totally organoderivatized surfaces are obtained from the reaction of [closo‐B12(OH)12]2− with acetic anhydride or benzoyl chloride. The resulting “closomers”, in which each cluster vertex is substituted with an organic ester moiety, can provide camouflaged modules of variable size, shape, charge, hydrophobicity, etc. and represent the first examples of this structural motif known in chemistry. The figure displays, in a space‐filling representation, the result of an X‐ray analysis performed with the dodecabenzoate ester derivative.

Synthesis and Applications of Perfunctionalized Boron Clusters

“…Later reports from the same laboratory further expanded the scope of substituents that could be installed on the B 12 (OH) 12 2− core through ester linkages. 72–74 …”

“…80 This remains the only reported peralkylation of dodecaborate, and the only homopersubstituted dodecaborate that contains B–C linkages. b) Halogenation 52,65–68 c) Hydroxylation 69–71,81 d) Carbamation 82 e) Carbonation 82 f) Esterification 72 g) Etherification 71 .…”

Dodeca(benzyloxy)dodecaborane, B12(OCH2Ph)12: A Stable Derivative ofhypercloso-B12H12

“…[3,9] The precursor for the synthesis of hypercloso-2, [closo-B 12 (OH) 12 ] 2À (1 2À ) [7] is especially attractive due to its sheath of twelve identical hydroxy functions. [7,10] The preceding communication [11] reports the synthesis of species in which the twelve hydroxy functions of 1 2À have been converted to carboxylic acid esters. These dodecafunctionalized structures in which twelve organic substituents emanate from the vertices of the icosahedral surface have been designated as closomers and differentiated from dendritic structures.…”

A Convenient Route to Diversely Substituted Icosahedral Closomer Nanoscaffolds

“…The chemical basis of these unique nanocarriers is the discovery of the very stable and icosahedral [ closo -B 12 (OH) 12 ] 2− , 1 , and its successful 12-fold derivatization to produce general structures now known as closomers. 4–6 The syntheses of fully substituted borane closomers, in which linker groups emanate from a rigid B 12 2− core, represent a novel architecture at the interface of boron and carbon chemistries.…”

“…The resulting monodisperse closomers can accommodate closely spaced radial substituents with variable size, hydrophilicity, ionic charges, and solvation properties. 6 A schematic representation of such a system is shown in figure 1.…”