Structure-Property Relationships of Inorganic-Organic Hybrid Semiconducting Se-Fe-Cu-CO Polymers.

A novel family of inorganic-organic-hybrid SeFe(CO)-dipyridyl two- and one-dimensional Cu polymers was synthesized via the three-component liquid-assisted grinding (LAG) of [Cu(MeCN)], inorganic cluster [SeFe(CO)] (), and rigid conjugated dipyridyls 4,4'-dipyridyl (dpy) and 1,2-bis(4-pyridyl)ethylene (bpee) or flexible conjugation-interrupted dipyridyls 1,2-bis(4-pyridyl)ethane (bpea) and 1,3-bis(4-pyridyl)propane (bpp). They included a cluster-linked 2D polymer, [(μ-Se)Fe(CO)Cu(MeCN)(dpy)] (), a cluster-pendant 1D chain, [(μ-Se)Fe(CO)Cu(dpy)] (), cluster-blocked 1D polymers, [(μ-Se)Fe(CO)Cu(L)] (, L = bpee, bpea), and a cluster-linked 2D polymer, [(μ-Se)Fe(CO)Cu(bpp)] (). The reversible dimensionality transformations of these three types of polymers accompanied by the change in coordination modes of were achieved by the LAG addition of /[Cu(MeCN)] or dipyridyl ligands. These polymers were found to possess tunable low-energy gaps (1.49-1.72 eV) that increased in the order regarding their structural features: cluster-linked and , cluster-blocked and , and cluster-pendant and [(μ-Se)Fe(CO)Cu(L)] (L = bpee, ; bpea, ), indicative of the importance of the participation of cluster . The measured electrical conductivities of , , and were 3.13 × 10, 2.92 × 10, and 2.30 × 10 S·cm, respectively, which were parallel for the trend in their energy gaps, revealing semiconducting behaviors, supported by XPS, XANES, and DFT calculations. The surprising semiconductivity of the conjugation-interrupted bpp-linked was mainly ascribed to electron transport via C-H···O(carbonyl) hydrogen bonds and aromatic C-H···π contacts within its closely packed 2D layers. Water-/light-stable polymers , , and were also demonstrated to exhibit excellent pseudo-first-order photodegradation toward nitroaromatics and organic dyes, where cluster-linked polymer performed the best, as predicted by its structural features and narrow energy gap.