The title compound, C(17)H(18)N(2)O(3), is approximately planar, owing in part to an intra-molecular bifurcated O-H⋯(N,O) hydrogen bond; the dihedral angle between the two aromatic rings is 23.86 (9)°. In the crystal struture, centrosymmetrically related mol-ecules associate into dimers via the eight-membered carboxyl-ate {⋯H-O-C=O}(2) synthon.

In the title compound, C(7)H(14)O(2), co-operative eight-membered homodromic rings of O-H⋯O hydrogen bonds connect the mol-ecules into strands along [100]. According to graph-set analysis, the descriptor of these cycles is R(4) (4)(8). The cyclo-pentane-ring adopts an envelope conformation ((C4)E).

In the title compound, C(4)HCl(2)NO(3), the essentially planar (maximum deviation = 0.023 Å for the ring O atom) mol-ecules form N-H⋯O hydrogen bonds between mol-ecules lying about inversion centers, forming eight-membered rings with an R(2) (2)(8) motif in graph-set notation.

Vicinal bis(trifluoroacetimidoyl chloride)s, a novel kind of fluorinated building block, were obtained from o-phenylenediamines in the presence of TFA, triethylamine, triphenylphosphine and tetrachloromethane. Based on these blocks, a new synthesis involving [2 + 2 + 2] cycloaddition reactions for trifluoromethylated benzo-fused eight-membered rings was disclosed.

Cyclic eight-membered hydrogen-bonded rings exist in the title compound, C(5)H(7)N(2)(+).C(7)H(5)O(2)(-), involving the 2-aminopyridinium and benzoate ions. Each benzoate ion has two intramolecular hydrogen bonds. 2-Aminopyridinium benzoate ion pairs are linked by N-H...O hydrogen bonds, with an N...O distance of 2.8619 (14) A.

The mol-ecular structure of the title mol-ecule, C12H8BrN3Se, is built up from fused selenazolo and pyridine rings, linked to a 2-bromo-aniline group. In the crystal, pairs of mol-ecules are linked by N-H⋯N hydrogen bonds into dimers, forming eight-membered ring motifs.

The formation of ?-aromatic circuits along a grossly warped nanographene, C80H30, containing five- and seven-membered rings inserted into six-membered mesh, reveals global ?-circuits at the edge backbone.

Biphenylene carbon sheets Although graphene forms two-dimensional sheets, other arrangements of rings could also assemble as flat sheers. Fan et al. synthesized an ultraflat biphenylene sheet consisting sp 2 -hybridized atoms forming four-, six-, and eight-membered on a gold surface. An adsorbed halogenated terphenyl molecule undergoes two-step interpolymer dehydrofluorination polymerization th...

The mol-ecule of the title compound, C(20)H(32)O(4), is built up from three fused five-membered, six-membered and seven-membered rings. The five-membered ring has an envelope conformation, whereas the six- and seven-membered rings have chair conformations. The crystal structure is stabilized by strong inter-molecular O-H⋯O hydrogen bonds, forming a three-dimensional network. The absolute config...

The title compounds, C17H20O2 (1) and C17H18O2 (2), are allyl-ated caged compounds. In (1), the carbon atoms bearing the allyl groups are far apart [2.9417 (17) Å], hence the expected ring-closing metathesis (RCM) protocol failed to give a ring-closing product. When these carbon atoms are connected by a C-C bond as in (2), the distance between them is much smaller [1.611 (3) Å] and consequently...