Structure–property relationship of dipyridyl−Cu polymers containing inorganic clusters Te/SeFe₃(CO)₉

This mini-review covers a novel series of 1D and 2D Te/SeFe₃(CO)₉-incorporated (Te, 1a; Se, 1b) Cu-based coordination polymers synthesized by the liquid-assisted grinding (LAG) method using predesigned compound [TeFe₃(CO)₉Cu₂(MeCN)₂] (1a-Cu₂(MeCN)₂) with rigid or flexible dipyridyl ligands, or three components of [SeFe₃(CO)₉]²⁻ (1b), [Cu(MeCN)₄]⁺, and dipyridyls. These polymers displayed various cluster coordination modes, including cluster-blocked [EFe₃(CO)₉Cu₂(L)]_n (E = Te, 1a-L-1D, Se, 1b-L-1D; L = 1,2-bis(4-pyridyl)ethylene (bpee), 1,2-bis(4-pyridyl)ethane (bpea)), cluster-pendant [SeFe₃(CO)₉Cu₂(dpy)₃]_n (1b-dpy-1D, dpy = 4,4′-dipyridyl) and [EFe₃(CO)₉Cu₂(L)_2.5]_n (E = Te, 1a-L-2D, Se, 1b-L-2D; L = bpee, bpea), cluster-linked [SeFe₃(CO)₉Cu₂(MeCN)(dpy)_1.5]_n (1b-dpy-2D) and [SeFe₃(CO)₉Cu₂(bpp)₂]_n (1b-bpp-2D, bpp = 1,3-bis(4-pyridyl)propane), as well as the unique cation-anion polymer [{Cu₂(bpp)₄}{(TeFe₃(CO)₉Cu)₂(bpp)}]_n (1a-bpp-CA). Their dimensionality expansions and reversible transformations accompanied with bonding pattern changes were achieved upon the addition of stoichiometric amounts of appropriate agents. These polymers exhibited pronounced semiconducting properties with tunable energy gaps and optical (dc) or electrical conductivities. The trend of their semiconductivities can be related to bonding patterns, where efficient electron communications were proved to stem from the existence of carbonyl ligands and electron-rich clusters 1a and 1b. In particular, water−/light-stable 1b-based polymers exhibited excellent photodegradation activities toward nitroaromatics and organic dyes, where the efficiency was further rationalized by their structural features and narrow energy gaps.