Conformationally rigid molecular and polymeric naphthalene-diimides containing C₆H₆N₂constitutional isomers

Abstract

Organic thin films based on naphtalenediimides (NDIs) bearing alkyls substituents have shown interesting properties as OLEDs, thermoelectrics, solar cells, sensors and organic electronics. However, the polymorphic versatility attributed to the...

Molecular Design and Crystal Chemistry of Polyfluorinated Naphthalene‐bis‐phenylhydrazimides with Superior Thermal and Polymorphic Stability and High Solution Processability

“…Substantial stability of the F3, F5 and F7 crystal phases is demonstrated in a wide temperature range, from RT to (at least) 250 °C (see Figure 4). A slightly higher stability is reported for the non‐fluorinated F0 species which showed XRPD pattern constancy up to 300 °C (decomposition starts above 320 °C–TG/DSC evidence) [22] . This behavior is herein paralleled by F3, which decomposes above 350 °C without any preceding phase transition.…”

“…As a rule, chloroform, dichloromethane, acetonitrile, and methanol demonstrated a poor aptitude in dissolving these species (<2 mg mL −1 ), while 1,4‐dioxane and N,N ‐dimethylformamide were the best performers (with solubilities as high as 40 mg mL −1 ). Specifically, the limited solubility of F0 (which, inter alia, surpasses that of its configurational isomers with m‐ or p‐ diamino aryls [22] ) is highly improved in the fluorinated derivatives when polar (but not protic) solvents are employed. This observation is in line with the more polar character of C−F bonds than C−H ones, both for the aliphatic and the aromatic fluorines [41] …”

“…The high solubility in several solvents is therefore a promising feature for the development of simple solution‐based film deposition strategies, which could not be achieved with similar NDI species bearing non‐fluorinated aromatic imide residues [22] …”

“…Accordingly, these soluble materials afforded highly crystalline powders and films, though often polyphasic [14,15,16] . Much higher thermal and polymorphic stabilities of imido/hydrazimido derivatives were expected and, indeed, obtained upon replacing n ‐alkyls chains with N ‐substituted aryl residues, from RT to well above 450 °C [22] . Quantum‐mechanical calculations (by DFT) and cyclovoltammetric (CV) measurements also revealed a significant lowering of the frontier orbital energies of the hydrazimido derivative (facilitating its use as an electron acceptor).…”

Tuning of energy levels, transport properties and device performance of naphthalenediimide derivatives by introduction of Michael addition reaction

“…The reaction mixture was heated for 20 h at the refluxing temperature. 33 The mixture was then cooled and the brown solid was suspended in 20 mL of methanol for 1 h. The suspension was centrifuged and the solid product was washed with cold methanol. Product 2.…”