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Nucleophilic substitution of tetrabromosubstituted naphthalene diimides (NDIs) with aniline was studied in detail to explore the regioselectivity as three different diamino-substituted regioisomeric products can be formed. We found that the regioselectivity of the nucleophilic disubstitution of 2,3,6,7-tetrabromonaphthalene diimide with aniline is dependent on reaction solvents and additives. In dichloromethane and chloroform without an additive the 2,7-diamino-3,6-dibromo-NDI isomer was formed regioselectively, while in DMF under similar reaction conditions the 2,3-diamino-6,7-dibromo isomer was observed as the major regioisomer. The third possible regioisomer 2,6-diamino-3,7-dibromo product was formed, if at all, in an insignificant amount. Tetrabutylammonium fluoride (TBAF) additive exerts a dramatic effect on the regioselectivity of this reaction, as in dichloromethane without TBAF the 2,7-diamino isomer was formed regioselectively, while without TBAF the 2,3-diamino isomer was formed exclusively. This remarkable effect of TBAF can be rationalized in terms of a deprotonation of the monoamino-tribromo-NDI generated in the first step of this sequential reaction as an intermediate by fluoride ions leading to an anionic species as indicated by UV-vis and NMR experiments whose electronic properties direct the regioselective attack of the second amine molecule. Our efforts led to the exclusively regioselective synthesis of 2,7-diamino-3,6-dibromo- and 2,3-diamino-6,7-dibromo-NDIs for the first time. [ABSTRACT FROM AUTHOR]

2,3,6,7-Tetrabromonaphthalene dianhydride has been synthesized by the bromination of naphthalene dianhydride with dibromoisocyanuric acid in excellent yield. The condensation of this dianhydride with 2,6-diisopropylaniline yielded the corresponding tetrabromo-substituted naphthalene diimide (NDI), which is a versatile precursor for the synthesis of core-tetrafunctionalized NDIs. Nucleophilic substitution of tetrabromo NDI with alkoxy, alkylthio, and alkylamino nucleophiles afforded a series of coretetrasubstituted NDI chromophores that complete the series of previously reported di- and trifunctionalized NDI derivatives. The effects of electronic nature and number of core substituents on the optical and electrochemical properties of NDIs have been investigated by UV-vis and fluorescence spectroscopy and cyclic voltammetry. The absorption maxima (629–642 nm) of tetraamino NDIs are strongly bathochromically shifted compared to those of other core-functionalized NDIs. [ABSTRACT FROM AUTHOR]

The condensation of the CH acidic heterocycles 4-alkyl-2,6-dioxo-1,2,5,6-tetrahydropyridine-3-carbonitrile (5a and b) and barbituric acid (15) with electron-rich thiophene aldehydes and benzaldehyde derivatives affords the respective monomethine dyes 10-13 and 17-19. The formylation of 5a,b and 15 with N,N'-diphenylformamidine or dibutylformamide in acetic anhydride and further reaction with 4-picolinium salts 9a,b provide the dimethine dyes 14 and 20a,b. Triple hydrogen bonding of the imide groups of merocyanine dyes 10-14 has been investigated by NMR titration experiments with melamine 21. Despite rather pronounced variations of the charge-transfer properties within the given series of dyes, minor changes of their binding constants have been observed. These results could be rationalized by semiempirical calculations that reveal small changes in the charge density at the oxygen functionalities involved in hydrogen bonding upon variation of the electron-donating carbocyclic or heterocyclic groups at the terminal double bond. Although the binding constants for triple hydrogen bonding between imides and melamines are rather weak in chloroform, they proved to be strong enough to facilitate dissolution of some of these dyes in aliphatic solvents by coordination to amphiphilic melamines and dipolar aggregation. UV-vis spectral changes observed in methylcyclohexane vs chloroform suggest the formation of colloidal assemblies through noncovalent polymerization. [ABSTRACT FROM AUTHOR]

Examines the synthesis of tetraphenoxy-substitute diazadibenzoperylenes from tetrachloroperylene tetracarboxylic acid bisanhydride. Properties of diazaarenes; Characterization of chromophoric systems by optical absorption and fluorescence spectroscopy; Basis of a X-ray crystal structure.

Here we report a general method for the synthesis of polycyclic aromatic dicarboximides (PADIs) by palladium-catalyzed annulation of naphthalene dicarboximide to different types of aromatic substrates. Reaction conditions were optimized by systematic variation of ligand, solvent, and additive. It was shown that solvent has a decisive effect on the yield of the reaction products, and thus 1-chloronaphthalene as solvent afforded the highest yield. By applying the optimized reaction conditions, a broad series of planar carbo- and heterocycle containing PADIs were synthesized in up to 97% yield. Moreover, this approach could be applied to curved aromatic scaffold to achieve the respective bowl-shaped PADI. Two-fold annulation was accomplished by employing arene diboronic esters, affording polycyclic aromatic bis(dicarboximides). The optical and electrochemical properties of this broad series of PADIs were explored as well.

A detailed study on bromination and subsequent imidization of perylene bisanhydride with cyclohexylamine is reported. The present results reveal that previously reported 1,7-difunctionalized perylene bisimides are presumably contaminated with the respective 1,6 regioisomers. N,N'-Dicyclohexyl-1,7-dibromoperylene bisimide 1,7-3 is obtained for the first time in isomerically pure form, and its structure is unequivocally confirmed by X-ray analysis. By using regioisomerically pure 1,7-dibromoperylene bisimide 1,7-3, 1,7-dipyrrolidinylperylene bisimides 4a-c and 1,7-dipyrrolidinylperylene bisanhydride 5 as well as the unsymmetrically difunctionalized 1-bromo-7-pyrrolidinyl- and 1-cyano-7-pyrrolidinylperylene bisimides 7 and 8 are synthesized in good yield.