The structure of the title compound, C20H18O2, consists of a dimeric arrangement of benzofuran molecules around an inversion centre, linked via C-H...O hydrogen bonds. There are also C-H...pi ring interactions. All these interactions result in the formation of infinite chains parallel to the [100] axis. The cyclobutane ring is puckered, with a dihedral angle of 29.03 (13) degrees between the tw...

We construct a nil ring R which has bounded index of nilpotence 2, is Wedderburn radical, and is commutative, and which also has a derivation δ for which the differential polynomial ring R[x; δ] is not even prime radical. This example gives a strong barrier to lifting certain radical properties from rings to differential polynomial rings. It also demarcates the strength of recent results about ...

Self-dimerizations of twenty three aromatic carboxylate and sulfonate ions from their electrophoretic mobilities in aqueous solution were estimated by capillary zone electrophoresis (CZE). The magnitudes of the self-dimerizations ascribed to pi-pi interactions of these aromatic anions were determined by CZE as dimerization constants (KD). Although the largest KD value of 1.2 dm3 mol(-1) for 9-a...

The effect of pressure on the crystal structure of salicylaldoxime has been investigated. The ambient-pressure phase (salicylaldoxime-I) consists of pairs of molecules interacting through oximic OH...O hydrogen bonds; taken with phenolic OH...N intramolecular hydrogen bonds, these dimers form a pseudo-macrocycle bounded by an R4 4(10) motif. The dimers interact principally via pi...pi stacking ...

in this paper, we present some inequalities for the co-pi index involving the some topological indices, the number of vertices and edges, and the maximum degree. after that, we give a result for trees. in addition, we give some inequalities for the largest eigenvalue of the co-pi matrix of g.

The local response to an external magnetic field normal to the molecular plane of naphthalene and anthracene was investigated via current density and magnetic shielding density maps. The Biot-Savart law shows that the deshielding caused by pi-ring currents in naphthalene is stronger for alpha- than for beta-protons due to geometrical factors. The shielding tensor of the carbon nuclei in both mo...

We give algorithms for the evaluation of sparse polynomials of the form P = p0 + p1x + p2x 4 + · · ·+ pN−1x 2 , for various choices of coefficients pi. First, we take pi = p i, for some fixed p; in this case, we address the question of fast evaluation at a given point in the base ring, and we obtain a cost quasi-linear in √ N . We present experimental results that show the good behavior of this...