Alkylation and addition to isocyanate of 2-(5-amino-3,4-dicyano-2H-pyrrol-2-ylidene)-1,1,2-tricyanoethanide. X-Ray crystal and molecular structures of methyl-, dimethyl-, dimethylaminoethylene- and propylaminocarbonyl-amino derivatives

Anion-tuning of supramolecular gel properties

“…With compound 1.28 the cationic species has a drastic influence on the gel formed. 79 The presence of the salts NaCl, KCl, CaCl 2 or …”

“…109 Many LMWG contain functional groups that are sensitive to the pH of their environment. 7,8,11,12,15,18,[69][70][71][72][73][74][75][76][77][78][79][80][81][82][83][84] These groups can be deprotonated or protonated according to the pH of the solution and this may remove or create important interactions vital to the gel tuning and/or formation resulting in a gel that can be tuned by changing the pH.…”

Supramolecular assembly in a Janus-type urea system

“…The urea group is in a syn conformation and directed away from the metal centre as in form II of the free ligand structure and hence is available to hydrogen bond to the acetate anion, forming the well-known hydrogen bonding motif. 18,30 This anion binding mode resembles analogous exogenous complexation of anions by ruthenium(II) bound thiourea ligands. 31 The strength of the coordination interactions holding the assembly together, as well as its close-packed nature, suggest that it should be stable in solution as well as in the solid state.…”

“…The disubstituted urea functionality adopts an anti conformation resulting from an intramolecular hydrogen bond from N(4)-H to the Lewis basic pyrazolyl nitrogen atom. 18 The carboxamide N(5)-H group also forms an intra-molecular hydrogen bond to the same pyrazolyl nitrogen atom. Such intramolecular hydrogen bonding is expected based on Etter's rules which state that intra-rather than intermolecular hydrogen bonding should dominate.…”

“…19,20 It is in contrast to the structure of many disubstituted ureas, however, such as N,N′-diphenylurea which adopt a syn conformation forming the characteristic urea -tape hydrogen bonding motif in which the two NH groups interact with the carbonyl oxygen atom of an adjacent urea to give a hydrogen bonded polymer. 21 In this case compound 1 adopts an eight-membered hydrogen bonded ring motif ( in graph set nomenclature 18 ) There are only weak C-H···O interactions with the carbonyl of the carboxamide group leading to a 1D chain of these V-shaped molecules. This structure is interesting in that it adopts an anti conformation of the urea group with intramolecular hydrogen bonding, even though the pyrazolyl nitrogen atom is acting as a bifurcated acceptor.…”