Structures of Bifunctional Molecules Containing Two Very Different Supramolecular Synthons: Carboxylic Acid and Strong π···π Stacking 1,8-Naphthalimide Ring

Abstract

A series of molecules containing a carboxylic acid and a 1,8-naphthalimide group joined by different linkers (HL C1 = CH2; HL C2 = CH2CH2; HL C3 = CH2CH2CH2; HL ophen = ortho-C6H4; HL C4 = para-C6H4; HL ala = S-CHCH3) have been prepared and structurally characterized. The structures of HL C1 , HL C3 , and HL ala are similar, with alternating hydrogen bonding of the carboxylic acids and π···π stacking interactions of the naphthalimide groups assembling the molecules into parallel chains that are linked into sheets by a second set of π···π stacking interactions. Hydrogen bonding and π···π stacking interactions of the naphthalimide groups also assemble HL C2 into chains, but the chains are alternately oriented at nearly right angles causing the interchain π···π stacking interaction to organize the chains in an open three-dimensional structure. Three of these open structural units interpenetrate forming a unique three-dimensional network. The rigid ortho-arene linker in HL ophen directs the orientation of the π···π stacking interaction of the naphthalimide rings to be at 60°; when combined with the hydrogen bonding interactions helical one-dimensional chains form that pack into a unique rhombohedral architecture. In the structure of HL C4 ·DMF, each acid group is hydrogen bonded with the dimethylformamide (DMF) molecule; the structure contains one-dimensional ribbons supported only by the π···π stacking interactions from the 1,8-naphthalimide groups. All six molecules show fluorescence in the 432–449 nm region. Overall these structural studies show that the 1,8-naphthalimide supramolecular synthon is extremely versatile because it can simultaneously enter into multiple noncovalent interactions.

ESIPT reaction of potential bioactive heterocyclic Schiff base: Atomic visualization coupled with in vitro spectroscopy

“…Another secondary interaction that is recurrent in the single crystal is p-p stacking between aromatic rings [27]. Both the Hbonding and p-p stacking interaction connect the adjacent units to develop a zigzag supramolecular framework in the crystalline CBMDP molecule.…”

Synthesis, crystal structure and EPR spectroscopic analysis of novel copper complexes formed from N-pyridyl-4-nitro-1,8-naphthalimide ligands

“…[1][2][3][4] More recently naphthalimide derivatives have been utilised as building blocks in metal based supramolecular architectures where their π-deficient nature and ability to be readily functionalised has been exploited giving rise to systems in which the extension of the structure occurs through π-based interactions. This work has largely been pioneered by Reger and co-workers who, over the last decade, have functionalized the 1,8-naphthalimide moiety at the imide nitrogen site, with various transition metal ion coordinating functional groups such as carboxylates, [5][6][7][8][9][10][11][12][13][14] pyrazoles [15][16][17][18][19] and other coordinating groups, 20 and studied the structural aspects of the resulting complexes.…”

Homochiral, Helical Coordination Complexes of Lanthanides(III) and Mixed-Metal Lanthanides(III): Impact of the 1,8-Naphthalimide Supramolecular Tecton on Structure, Magnetic Properties, and Luminescence

“…The resulting colorless block crystals were collected and washed with methanol to yield 0.021 g of 5 in a 34% yield. (6). Compound 6 was synthesized in a similar manner to compound 1 but with terbium nitrate hexahydrate (0.030 g, 0.066 mmol).…”