Non-concerted [2+2] and [4+2] cycloadditions between N,N-dimethylanilino-substituted 1,1,2,4,4-pentacyanobuta-1,3-diene and 4-ethynyl-N,N-dimethylaniline are controlled by solvent polarity and provide access to a highly functionalised 6,6-dicyanopentafulvene featuring an intense, low-energy charge-transfer band and to an unusual spirocyclic zwitterion, characterised by X-ray analysis.

In the title compound, C17H13Cl2NO2, the H atom of the -OH group is transferred to the N atom of the imine, forming a zwitterion. Thus, there is a intra-molecular O⋯H-N, rather than O-H⋯N, hydrogen bond, which forms a six-membered ring.

The Back Cover picture illustrates the attachment of iodine atoms onto the headgroup of an amphiphilic zwitterion, which leads to the formation of a bicontinuous cubic liquid-crystalline assembly with a primitive-type infinite periodic minimal surface. More information can be found in the Communication by T. Ichikawa, H. Ohno and co-workers on page 439 in Issue 5, 2016 (DOI: 10.1002/open.201600...

The treatment of cyclopropanes having donor and acceptor substituents at the vicinal positions on the cyclopropane ring with a Lewis acid readily generates a 1,3-zwitterion, which reacted with allylsilanes to produce cycloadducts and allylic products. It was found that the yield of the cycloadduct depends on the steric demand of the alkyl substituents on the silicon atom.

The title compound, C(12)H(8)N(2)O(4), crystallizes as a zwitterion in which the pyridyl N atom is protonated. The dihedral angle between the benzene and pyridinium rings is 27.9 (2)°. In the crystal, N-H⋯O hydrogen bonds link adjacent zwitterions into a three-dimensional structure.

A novel zwitterion acting as both a functional monomer and a crosslinker with the protein-resistant ability concomitantly was synthesized for preparing water compatible diclofenac imprinted polymers. This new imprinted polymer showed high imprinting efficiency for template and strong anti-protein adsorption in aqueous medium.

The organic mol-ecule of the title compound, C(7)H(11)NO(4)S·CH(3)OH, is a zwitterion and its furan ring displays positional disorder [occupancy 0.563 (5):0.437 (5)]. The crystal structure is extended into a three-dimensional supra-molecular architecture through inter-molecular O-H⋯O and N-H⋯O hydrogen bonds with participation of the methanol solvent mol-ecules.

The title compound, C(13)H(20)NO(3)P, exists as a zwitterion: the phospho-nic acid group has transferred its H atom to the amino group. The piperidine ring adopts a chair conformation. Mol-ecules are linked via hydrogen bonding to form a linear chain.