A chiral
carboxylic acid, (−)-N-(2-imidazol-5-yl-1-carboxyethyl)-1,8-naphthalimide
(Hbnap), bearing imide and imidazole functionalities with some structural
relevance to tryptophan and histidine amino acids, was designed. Various
solvates and salts of Hbnap were synthesized and structurally characterized,
namely, Hbnap·H2O (1), 4Hbnap·MeOH·3H2O (2), Hbnap·DMSO {DMSO = dimethyl sulfoxide}
(3), Hbnap·DMF {DMF = N,N′-dimethylformamide} (4), Hbnap·DMA
{DMA = N,N′-dimethylacetamide} (5), Hbnap·2quinoline (6), Hbnap·pyridine
(7), bnap·Hdbu·2H2O {dbu = 1,8-diazabicyclo[5.4.0]undec-7-ene}
(8), [H2bnap]Br·0.5MeOH (9), [H2bnap]I·0.5MeOH (10), [H2bnap]2SO4·DMF·H2O (11), and [H2bnap]NO3 (12). Their packing patterns were analyzed in detail,
showing that an interplay of hydrogen bonds, aquation, and π-stacking
control the formation of distinct one-, two-, or three-dimensional
(1D, 2D, or 3D) supramolecular assemblies. The H-bonded 2D underlying
networks of solvates 1–8 were topologically
classified revealing three distinct topological types, namely, an
undocumented topology in 1 and the 3,4L127 and skl topologies in 2 and 3–8, respectively. In contrast, the [H2bnap]+ salts 9–12 show
H-bonded underlying networks that are quite distinct not only in the
topology (2C1 in 9 and 10, kgd in 11, and lon in 12) but also in the dimensionality that increases from 1D in halide
salts 9 and 10 to 2D in sulfate derivative 11 and 3D in nitrate compound 12. Thermogravimetric
analysis studies on the removal of DMSO, DMA, and dbu show that packing
by the zwitterionic form of the Hbnap host and the formation of salts
impede the elimination of solvent in comparison with conventional
hydrogen bonded hosts. UV–vis and fluorescence emission studies
were also performed showing that different solvates and salts exhibit
strong emission bands with distinct maxima in the 428–487 nm
region. A significant enhancement of the fluorescence intensity in
comparison with the free Hbnap host molecule occurred in all compounds.