Synthesis, Solution, and Solid State Properties of Homological Dialkylated Naphthalene Diimides—A Systematic Review of Molecules for Next-Generation Organic Electronics

Abstract

This systematic study aimed at finding a correlation between molecular structure, solubility, self-assembly, and electronic properties of a homological series of N-alkylated naphthalene diimides (NDIs). NDIs are known for their n-type carrier mobility and, therefore, have potential in the field of organic electronics, photovoltaics, and sensors. For the purpose of this study, nine symmetrical N,N′-dialkylated naphthalene diimides (NDIC3-NDIC11) were synthesized in the reaction of 1,4,5,8-naphthalenetetracarboxylic dianhydride with alkylamines ranging from propyl- to undecyl-. The NDIs were characterized by spectroscopic (NMR, UV-Vis, FTIR), microscopic, and thermal methods (TGA and DSC), and X-ray diffraction (XRD). Our experimental study, extensively referring to findings reported in the literature, indicated that the NDIs revealed specific trends in spectroscopic and thermal properties as well as solubility and crystal morphology. The solubility in good solvents (chloroform, toluene, dichlorobenzene) was found to be the highest for the NDIs substituted with the medium-length alkyl chains (NDIC5–NDIC8). Systematic FTIR and XRD studies unraveled a distinct parity effect related to the packing of NDI molecules with odd or even numbers of methylene groups in the alkyl substituents. The NDIs with an even number of methylene groups in the alkyl substituents revealed low-symmetry (P1−) triclinic packing, whereas those with an odd number of carbon atoms were generally monoclinic with P21/c symmetry. The odd–even parity effect also manifested itself in the overlapping of the NDIs’ aromatic cores and, hence, the π-π stacking distance (dπ-π). The odd-numbered NDIs generally revealed slightly smaller dπ-π values then the even-numbered ones. Testing the NDIs using standardized field-effect transistors and unified procedures revealed that the n-type mobility in NDIC6, NDIC7, and NDIC8 was 10- to 30-fold higher than for the NDIs with shorter or longer alkyl substituents. Our experimental results indicate that N,N′-alkylated NDIs reveal an optimum range of alkyl chain length in terms of solution processability and charge transport properties.

Mild selective photochemical oxidation of an organic sulfide using OxP-polyimide porous polymers as singlet oxygen generators

“…The presence of two C=O (str.) peaks in OxP-N and OxP-P at 1730 and 1680 cm −1 is similar to that for previously reported naphthalene diimides [ 56 ] and perylene diimides [ 57 ]. According to the particle size distributions of the materials obtained by DLS (Figure S3), OxP-B and OxP-P consist of large particles with diameters over 25 µm and a broad size distribution with particle diameters exceeding 1000 µm (the detection limit of the DLS instrument).…”

Polyfluorinated Naphthalene-bis-hydrazimide for Solution-Grown n-Type Semiconducting Films

“…In TF-F5 films, the on–off ratio is about 10 4 and the threshold voltage V TH and the subthreshold slope SS are −10.1 V and 1.1 V/dec, respectively. Note that the carrier mobility value of TF-F5, far from being exceptional, falls above the normal range found for axially substituted NDI derivatives (10 –4 cm 2 V –1 s –1 , see the compilation present in ref ), whereas higher mobility values (up to 2 cm 2 V –1 s –1 ) were obtained in bay-fused aromatic moieties (see, e.g., compound 95 presented in ref ). For a solution-processed film of this type and in the absence of specific precautions, this is considered appreciable and points to higher values for proper process optimization, e.g., after insertion of self-assembled monolayers in the BGTC architecture …”

Aggregation‐Induced Emission of Naphthalene Diimides: Effect of Chain Length on Liquid and Solid‐Phase Emissive Properties

“…The synthesis is a one‐step reaction through the commercially‐available naphthalene dianhydride with C3‐C8 amines (see supporting information). Although some studies of the effect of elongating the chains in NDIs have been performed, they have been devoted to study their supramolecular structures on highly oriented pyrolytic graphite (HOPG) surfaces, [37] thermal expansion behavior on thin films [38] and field‐effect transistors, [39] but none have focused their attention on the study of AIE behavior. We demonstrate how elongating chains at the imide position can bring a change in the emission properties in an aggregated form in the liquid and solid states, allowing quantification through a color palette used in several applications.…”