Synthesis, Crystal Structure, and Physical Property of Sterically Unprotected Thiophene/Phenylene Co-Oligomer Radical Cations: A Conductiveπ-πBonded Supermolecularmeso-Helix

Stable Radical Cations and Their π-Dimers Prepared from Ethylene- and Propylene-3,4-dioxythiophene Co-oligomers: Combined Experimental and Theoretical Investigations

Co-oligomers composed of two 3,4-ethylenedioxythiophene (EDOT) units and two or three 3,4-propylenedioxythiophene (ProDOT) units, i.e., 2E2P_Et and 2E3P_Et, were newly synthesized together with the ProDOT trimer 3P_Me. On the basis of cyclic voltammetry, the gaps between the first and second oxidation potentials (ΔE^1-2) of 2E2P_Et and 2E3P_Et were found to be larger than that of the previously synthesized ProDOT tetramer 4P_Hex. These co-oligomers gave the fairly stable radical cations 2E2P_Et^•+ and 2E3P_Et^•+ by chemical oxidation with AgSbF₆. The disproportionation of 2E2P_Et^•+ and 2E3P_Et^•+ into neutral and dicationic species, which was observed for 4P_Hex^•+, was inhibited in accord with the larger ΔE^1-2. Additionally, the formation of the π-dimers (3P_Me)₂²⁺, (2E2P_Et)₂²⁺, and (2E3P_E)₂²⁺ was clearly observed in dichloromethane solution at low temperatures with UV-vis-NIR spectroscopy. Furthermore, the π-dimerization enthalpies of 2E2P_Et^•+ and 2E3P_Et^•+ were greater than that of 3P_Me^•+, suggesting the formation of fully π-contacted structures. The structures of the π-dimers were optimized at the B97D3 method, and the calculated absorption spectra of the π-dimers obtained using TD-DFT methods were in reasonable agreement with the observed ones, supporting the reliability of the calculated structures.

Single-Crystal X-ray Structures of conductive π-Stacking Dimers of Tetrakis(alkylthio)benzene Radical Cations

Salts containing radical cations of 1,2,4,5-tetrakis(isopropylthio)benzene (TPB) and 1,2,4,5-tetrakis(ethylthio) benzene (TEB) have been successfully synthesized with . These newly synthesized salts have been characterized by UV-Vis absorption, EPR spectroscopy, conductivity measurement, single crystal X-ray diffraction analysis as well as DFT calculation. This study raises the first crystal structure of conductive π-stacking radical cation with single phenyl ring and reveals their conductivity has relationship with the stack structure which affected by the substituent.

Odd-electron-bonded sulfur radical cations: X-ray structural evidence of a sulfur-sulfur three-electron σ-bond

The one-electron oxidations of 1,8-chalcogen naphthalenes Nap(SPh)2 (1) and Nap(SPh)(SePh) (2) lead to the formation of persistent radical cations 1(•+) and 2(•+) in solution. EPR spectra, UV-vis absorptions, and DFT calculations show a three-electron σ-bond in both cations. The former cation remains stable in the solid state, while the latter dimerizes upon crystallization and returns to being radical cations upon dissolution. This work provides conclusive structural evidence of a sulfur-sulfur three-electron σ-bond (in 1(•+)) and a rare example of a persistent heteroatomic three-electron σ-bond (in 2(•+)).

Helicity discrimination in N,N'-dibenzoyl-1,2,3,4,7,8,9,10-octahydro-1,10-phenanthrolines and their thiono- and selenocarbonyl analogues by inclusion complexation with chiral diols

X-ray crystallographic analysis of the title compounds revealed that they assume a folded helical conformation of an approximate C2 symmetry in the solid state. Dithioamide 5b, diselenoamide 5c and monoselenoamide 5d were resolved to enantiomers by inclusion crystallization with optically active diols (TADDOLs). The absolute configuration of the guest molecules in the complexes 5b·6a, 5c·6a and 5d·6a was assigned as P. The optical activity of the resolved compounds is manifested by their CD spectra showing relatively strong Cotton effects in the region of thionoamide and selenoamide n–π* transition. The optically active thiono- and selenoamides are configurationally labile compounds and gradually racemize in solution but they are stable in the form of the inclusion complexes. The first-order kinetics of the racemization in solution allowed us to assign the racemization barriers by the spectropolarimetric measurements.

Isolation and characterization of the cycloparaphenylene radical cation and dication

Charged nanobelts: The radical cation and the dication of [8]cycloparaphenylene ([8]CPP) were prepared and isolated as hexahaloantimonate salts by the one- or two-electron chemical oxidation of [8]CPP with NOSbF6 or SbCl5 . ESR spectroscopy of CPP(.+) and single-crystal X-ray analysis of CPP(2+) demonstrated that the spin and charge were equally and fully delocalized over the para-phenylene rings.