| Popis: |
Our previous EPR studies dealt with the contrasting behaviour of the lamellar C8OCu, as against the columnar C8Cu/C10Cu. X-ray and EPR studies of C n , Cu(n = 6–12) and CnOCu(n = 6–12) presented here, however, indicate that some members exhibit anomalous behaviour within each series. Thus C6Cu, C8Cu, C10Cu and C12Cu (even members) show a single exchange-narrowed strong asymmetric g⊥ along with a weak g‖ in pure solids. Interestingly, C7Cu and C9Cu (odd members) show hyperfine quartets in g‖, indicating weak or no exchange. C7Cu shows a single g⊥, conforming to the axial symmetry in CnCu. However, C9Cu is rather unique: gives three different mesophases and exhibits non-axial behaviour. Crystal structure for C9Cu and C7Cu reported here for the first time, indicate that the former has a structure similar to that of C7Cu. However, C7Cu, which also has z = 1 and belongs to the same triclinic space group, has a close interaction between two molecules at the opposite corners of the ab plane in the unit ... |
