Different Contributions of Aliphatic and Conjugated Organic Cations to Both the Crystal and Electronic Structures: Three Hybrid Iodoargentates Showing Two Isomers of the (AgI sub(2)) super(-) Chain

Three new hybrid iodoargentates (H sub(2)pipe) sub(0.5)( alpha -A gI sub(2)) (1), (Me sub(2)teda) sub(0.5)( alpha - AgI sub(2)) (2), and (H sub(2)dpe) sub(0.5)( beta -AgI sub(2)) (3) have been synthesized under solvothermal conditions, whereby the aliphatic organic cations (H sub(2)pipe) super(2+) and (Me sub(2)teda) super(2+) (pipe = piperazine, teda = triethylenediamine) and the conjugated organic cation (H sub(2)dpe) super(2+) [dpe = 1,2-di(4-pyridyl)ethylene] exhibit different contributions to both the crystal and electronic structures. The (H sub(2)pipe) super(2+) and (Me sub(2)teda) super(2+) cations direct the formation of alpha -type (AgI sub(2)) super(-) polyanionic chains and influence the bandgaps of 1 and 2 indirectly by modulating the iodoargentate anionic structures. By contrast, the (H sub(2)dpe) super(2+) cation directs the formation of a novel beta -type (AgI sub(2)) super(-) chain and changes the bandgap of 3 directly to make up the bottom of the conduction band. From 1 and 2 to 3, a direct to indirect bandgap transformation and reduced bandgap can be observed (3.74, 2.88, and 1.99 eV for 1-3, respectively). Relative to the bandgap of bulk AgI sub(2), the bandgaps of 1 and 2 show a blueshift as a result of the quantum confinement effect, whereas the bandgap of 3 shows a redshift owing to the direct participation of the conjugated cation (H sub(2)dpe) super(2+) in adjusting the bandgap. Three new hybrid iodoargentates that show two isomers of 1D (AgI sub(2)) anionic chains have been synthesized under solvothermal conditions. Studies indicate that aliphatic and conjugated organic cations have different contributions to both the crystal and electronic structures.