Background: Cyclic oligomeric silsesquioxanes (COSSs) composed of an inorganic Si-O-Si cycle
with different silicon atom number from 3 to 12 and organic substituent groups are the promising precursors
for organic-inorganic hybrids. COSSs includes two categories: metallic cyclic oligomeric silsesquioxanes
(mCOSSs) and macrocyclic oligomeric silsesquioxanes (MOSSs). Since pioneer works were done by Russian
scientists, including Zhdanov, Shchegolikhina, and Lindeman, et al. in the 1990s, COSS chemistry has
emerged as a new research field in organic silicon chemistry.
Methods: Three major methods, including cation exchange strategy, ligand exchange strategy and cleavage of
polymetallasiloxane strategy, have been used to prepare a variety of COSSs.
Objective: The aim of this article is to present a comprehensive understanding of mCOSSs and MOSSs in synthesis
and potential applications.
Results: mCOSSs and MOSSs have exhibited excellent performances when they are employed as the precursors
of magnetic, organic-inorganic, and porous materials.
Conclusion: The article reviews the major developments of COSSs in synthesis, characterization, functionalization,
and excellent performances over the last decades. Future research will focus on the synthesis advance
and various applications of COSSs.