resolver

2 General introduction
The aim of this chapter is to give a general introduction on the research progress of metalorganic
frameworks (MOFs) including the origin of MOFs, their chemistry, structural
features, synthetic approaches, modification on the structure as well as their applications.
2.1 Origin of MOFs - Coordination polymers
In 1833, J. J. Berzelius firstly use the term “polymer” to describe any compound that could
be formulated as consisting of multiple units of a basic building block. [1] Later, Werner for
the first time, proposed the correct structure [Co(NH3)6]Cl3 for coordination compounds
containing complex ions in 1893, which developed the groundwork for the study of
coordination polymers (CPs). In 1916, to define dimers and trimers of various cobalt(II)
ammine nitrates, the term “CPs” was firstly employed by Y. Shibata [2] and has been
continuously used in the scientific literature since the 1950's. Moreover, the first review
on CPs was published in 1964. [3] The International Union of Pure and Applied Chemistry
(IUPAC) Red Book of inorganic nomenclature from 2005 gives the following definition of
coordination compounds: “A coordination compound is any compound that contains a
coordination entity. A coordination entity is an ion or neutral molecule that is composed of
a central atom, usually that of a metal, to which is attached a surrounding array of atoms
or groups of atoms, each of which is called a ligand”. [4] Consequently, CPs can be
conceptually considered as coordination compounds with extended arrays structures of
one, two or three dimensions (Figure 2.1). [5] Typically, CP consists of two central
components: metal ions (serving as connectors) and ligands (serving as linkers). Apart
from these two components, blocking ligands, counter-anions, non-bonding guests or
template molecules can be also included (Figure 2.2). The number and orientation of the
binding sites (i.e. coordination numbers and geometries) are the important
characteristics of the connectors and linkers. Their combination in numerous ways via a
self-assembly enables the formation of practically an infinite number of CPs (Figure 2.1).