The effect of the linking topology on the electrochemical and spectroelectrochemical properties of carbazolyl substituted perylene bisimides

Photothermal Conversion Perylene-Based Metal-Organic Framework with Panchromatic Absorption Bandwidth across the Visible to Near-Infrared

Recently, facilely designable metal-organic frameworks have gained attention in the construction of photothermal conversion materials. Nonetheless, most of the previously reported photothermal conversion metal-organic frameworks exhibit limited light absorption capabilities. In this work, a distinctive metal-organic framework with heterogeneous periodic alternate spatial arrangements of metal-oxygen clusters and perylene-based derivative molecules was prepared by in situ synthesis. The building blocks in this inimitable structure behave as both electron donors and electron acceptors, giving rise to the significant inherent charge transfer in this crystalline material, resulting in a narrow band gap with excellent panchromatic absorption, with the ground state being the charge transfer state. Moreover, it can retain excellent air-, photo-, and water-stability in the solid state. The excellent stability and broad light absorption characteristics enable the effective realization of near-infrared (NIR) photothermal conversion, including infrequent NIR-II photothermal conversion, in this perylene-based metal-organic framework.

Naphthalene Phthalimide Derivatives as Model Compounds for Electrochromic Materials

Electrochromism of organic compounds is a well-known phenomenon; however, nowadays, most research is focused on anodic coloring materials. Development of efficient, cathodic electrochromic materials is challenging due to the worse stability of electron accepting materials compared with electron donating ones. Nevertheless, designing stable cathodic coloring organic materials is highly desired-among other reasons-to increase the coloration performance. Hence, four phthalimide derivatives named 1,5-PhDI, 1,4-PhDI, 2,6-PhDI and 3,3'-PhDI were synthesized and analyzed in depth. In all cases, two imide groups were connected via naphthalene (1,5-PhDI, 1,4-PhDI, 2,6-PhDI) or 3,3'-dimethylnaphtidin (3,3'-PhDI) bridge. To observe the effect of chemical structure on physicochemical properties, various positions of imide bond were considered, namely, 1,5- 1,4- and 2,6-. Additionally, a compound with the pyromellitic diimide unit capped with two 1-naphtalene substituents was obtained. All compounds were studied in terms of their thermal behavior, using differential calorimetry (DSC) and thermogravimetric analysis (TGA). Moreover, electrochemical (CV, DPV) and spectroelectrochemical (UV-Vis and EPR) analyses were performed to evaluate the obtained materials in terms of their application as cathodic electrochromic materials. All obtained materials undergo reversible electrochemical reduction which leads to changes in their optical properties. In the case of imide derivatives, absorption bands related to both reduced and neutral forms are located in the UV region. However, importantly, the introduction of the 3,3'-dimethylnaphtidine bridge leads to a noticeable bathochromic shift of the reduced form absorption band of 3,3'-PhDI. This indicates that optimization of the phthalimide structure allows us to obtain stable, cathodic electrochromic materials.

Influence of imide-substituents on the H-type aggregates of perylene diimides bearing cetyloxy side-chains at bay positions

A series of perylene-3,4:9,10-tetracarboxylic acid diimides (PDIs, namely TYR-PDI, AEP-PDI, CET-PDI, ANP-PDI and KOD-PDI), comprising long linear cetyloxy side-chains functionalized at the 1,7-bay positions and the different substituents (i.e., hydrophobic/hydrophilic segments) symmetrically linked at the two imide-positions of the perylene core were synthesized to investigate the influence of imide-substituent patterns on the aggregation behaviours of PDIs. The photophysical properties of these PDIs were studied by UV-Vis absorption, fluorescence and time-resolved photoluminescence spectroscopy. The differences in the photophysical properties of the PDIs indicate (i) blue-shifted and broadening absorption properties in both solution and thin-films, (ii) red-shifted and broadening fluorescence behavior at their emission maximum in solution, however, blue-shifted fluorescence behavior in thin-films, and (iii) obviously longer fluorescence life-times corresponding to the existence of rotationally displaced H-type aggregates. The formation of short-range ordered rod-like microstructures through face-to-face alignment of columnar rectangular H-type PDI aggregates was rationalized by scanning electron microscopy. The X-ray diffraction study revealed that the formation of well-defined columnar rectangular (Col_rp) H-type PDI aggregates indicated a nearly constant intracolumnar stacking distance of ∼3.9 Å for all PDIs. All of these findings were consistent with the formation of hydrophobic/hydrophilic interactions between the imide-substituents in addition to the strong hydrophobic π-π stacking interactions between the conjugated perylene cores, which were enforced in the H-type PDI aggregates that spontaneously self-organized into Col_rp structures.

Benzothiophene-flanked diketopyrrolopyrrole polymers: impact of isomeric frameworks on carrier mobilities

The influence of isomeric backbones on field-effect properties in benzothiophene-flanked diketopyrrolopyrrole polymers was investigated.