DPP Pigments Research Articles

Diketopyrrolopyrrole (DPP) pigments

Abstract Since their industrial introduction in the 1980s, DPP pigments now constitute a highly important group of high-performance carbonyl pigments. The DPP system was first discovered by accident in 1974, and was subsequently re-investigated by Ciba Geigy who recognized its potential to provide commercial organic pigments. DPP pigments exhibit strong similarities compared with quinacridone pigments, in terms of their molecular and crystal structures and their properties, including low solubility and excellent fastness properties. X-ray crystal structural analysis has demonstrated that their technical performance is the result of intermolecular hydrogen bonding and π–π stacking interactions in the crystal lattice structure. Based on a simple retrosynthetic analysis, an efficient synthetic process was developed by Ciba Geigy for their large-scale manufacture. DPP pigments currently provide orange through to reddish violet shades and have become of special importance in providing brilliant saturated red shades with the outstanding durability required for applications such as automotive paints.

STRUCTURAL, ELECTRONIC AND OPTICAL PROPERTIES OF THIOPHENE AND THIENOTHIOPHENE CONTAINING DIKETO-PYRROLO-PYRROLES (DPPs) IN POLAR APROTIC SOLVENTS

Thiophene (T) and thienothiophene (TT) containing 2,5-dihydro-pyrrolo[3,4-c]pyrrole-1,4-dione (DPP) compounds were prepared according to the succinic ester route from the corresponding heterocyclic nitrile precursors. As is typical of most DPP pigments, the new compounds showed high thermal stability and could be obtained in pure form as determined by elemental analysis. The bulk properties and molecular structure of the compounds were further characterized by thin film, powder XRD and solid state CP-MAS 13 C NMR. Density functional theory (DFT) and time-dependent (TD) DFT were employed to study the geometric and electronic structures of these molecules in the ground state. The optical properties were investigated by UV-Vis absorption and fluorescence spectroscopies in dimethylsulfoxide (DMSO) and N,N-dimethylacetamide (DMA), which revealed that the absorption maximum of the thiophene diketo-pyrrolo-pyrroles (TDPP) and thienothiophene diketo-pyrrolo-pyrroles (TTDPP) in solution were red shifted up to 25 nm and 60 nm, respectively, relative to Pigment Red 255 (PhDPP), while a new absorption band appeared at longer wavelengths in N-methyl pyrolidone (NMP) and N,N′-dimethylpropylene urea (DMPU) which is ascribed to solvent induced charge transfer (CT) complex. The molecular conformations and absorption spectra of TDPP and TTDPP were characterized by quantum chemical methods in order to better understand the observed behavior.

Fluorescent materials for pH sensing and imaging based on novel 1,4-diketopyrrolo-[3,4-c]pyrrole dyes

New optical pH-sensors relying on 1,4-diketopyrrolo-[3,4-c]pyrroles (DPPs) as fluorescent pH-indicators are presented. Different polymer hydrogels are useful as immobilization matrices, achieving excellent sensitivity and good brightness in the resulting sensor. The operational pH can be tuned over a wide range (pH 5-12) by selecting the fine structure of the indicator and the matrix. A ratiometric sensor in the form of nanoparticles is also presented. It is suitable for RGB camera readout, and its practical applicability for fluorescence imaging in microfluidic systems is demonstrated. The indicators are synthesized starting from the commercially available DPP pigments by a straightforward concept employing chlorosulfonation and subsequent reaction with amines. Their sensitivity derives from two distinct mechanisms. At high pH (>9), they exhibit a remarkable alteration of both absorption and fluorescence spectra due to deprotonation of the lactam nitrogen atoms. If a phenolic group is introduced, highly effective fluorescence quenching at near-neutral pH occurs due to photoinduced electron transfer (PET) involving the phenolate form.

ChemInform Abstract: Preparation of Red Dyes Derived from Diketo‐pyrrolo‐pyrrole Based Pigment and Their Properties for LCD Color Filters.

AbstractRed DPP pigments (I) are prepared as an alternative to increase the contrast ratio and brightness which are crucial requirements in LCD color filter sector.

Synthesis and properties of some new N, N′-disubstituted 2,5-dihydro-1,4-dioxo-3,6-diphenylpyrrolo[3,4- c]pyrroles

A variety of substituents have been introduced on the nitrogen atoms of the parent 2,5-dihydro-1,4-dioxo-3,6-diphenylpyrrolo[3,4- c]pyrrole upon treatment with alkylating agents in a basic medium. Crystal structure as well as absorption and fluorescence properties of the new DPP pigments so obtained is discussed.

DPP Chemistry—Continuous Innovation

AbstractFor Abstract see ChemInform Abstract in Full Text.

DPP chemistry — continuous innovation

Since their introduction some 15 years ago DPP pigments have established themselves very well in the market and have quickly become the standard for opaque reds in high performance applications. In this review the story of the success of this latest class of pigments will be outlined with emphasis on its chemical and physical properties. After a historical survey of the synthesis and reactivity of the DPP molecule, the correlation between molecular and solid state structure and its implications on physical properties will be discussed in general and with special stress on the importance of intermolecular hydrogen bonding. Finally, a series of examples will show briefly how application-relevant properties of DPP pigments can be optimised, eg improved colourspace by new crystal modifications or solid solutions, opacity/transparency control by appropriate ripening conditions, improved heat stability by growth-controlling additives and better rheological properties by adequate surface treatments.

Coloured Glass-fibre Reinforced Composites

Coloured glass-fibre reinforced composites of conventional di-glycidylether of bis-phenol-A and novel heterocyclic pigments. 1,4-di-keto-pyrrolo[3,4-c]pyrrole (DPP) were prepared, using di-ethylenetriamine as curing agent and evaluated for their physical properties (such as density. % resin content and % void content) and mechanical properties (such as flexural strength, interlaminar shear strength and shore-D hardness). The laminates were also evaluated for their chemical resistance and electric properties. It is observed that the incorporation of DPP pigments imparts colour, but does not deteriorate the above mentioned properties of the DGEBA based glass-fibre reinforced composite.