Hydrogen bonding is a kind of noncovalent interaction that holds a very important position in the field of supramolecular chemistry. In the past few years, hydrogen bonding mediated supramolecular polymer has become a hot research topic in supramolecular chemistry. The construction of excellent hydrogen bonding building blocks lies the basis for the area. Among that, triply and quadruply hydrogen bonded systems are widely used for the construction of supramolecular assemblies. In this article, we summarize the progress and applications of triply and quadruply hydrogen bonded systems. We put our emphasis on the design principles of such systems and the factors affecting the stability of each system.

Contents
1 Introduction
2 Triply hydrogen bonded systems and their
applications
2.1 ADA·DAD triply hydrogen bonded systems
2.2 DDA·AAD triply hydrogen bonded systems
2.3 DDD·AAA triply hydrogen bonded systems
3 Quadruply hydrogen bonded systems and their applications
3.1 Quadruply hydrogen bonded systems of separated hydrogen bonding building blocks
3.2 Self-complementary quadruply hydrogen bonded system with DADA·ADAD hydrogen bonding sites
3.3 Self-complementary quadruply hydrogen bonded system with DDAA·AADD hydrogen bonding sites
3.4 Complementary quadruply hydrogen bonded system with DAAD·ADDA hydrogen bonding sites
3.5 Quadruply hydrogen bonded system with AAAA·DDDD hydrogen bonding sites
3.6 Quadruply hydrogen-bonded molecular duplexes free of secondary electrostatic interactions
3.7 Other quadruply hydrogen bonded systems
4 Conclusion and outlook