Rosarina Carpignano

Quantitative structure-property relationships study of azo dyes using partial least Squares analysis in latent variables (PLS)

Abstract The light, washing, alkali and perspiration fastness of a series of azo dyes are analysed as a function of physicochemical substituent descriptors by the PLS method. The analysis permits relation of the fastness properties to the structural features and the development of a model which can be used to predict the fastness of new dyes of the same series.

NMR investigation of azo disperse dyes

Abstract The 13 C-NMR spectra of a series of monoazo disperse dyes derived from diethylaminoazobenzene were measured and analysed. Depending on the nature and orientation of the substituent in the dyes, different conformers, resultant from inner rotation around the CN bonds, could be identified. The structural data provide a new tool for studies on dye-substrate interactions.

VESICLE PRECURSORS IN THE DYEING OF POLYESTER WITH DISPERSE DYES

Abstract The use of double tailed surfactants suitable for the preparation of synthetic vesicles and the resort to sonication for the setting up of dyebaths in the dyeing of polyester fabrics with a disperse dye is proposed. The dye, having excellent fastnesses, belongs to the diethylamino-azobenzene series and has been designed by chemo-metric procedures. In a selected number of experiments, excellent results are obtained from both the points of view of dyebath exhaustion and uniformity of coloration. Further investigation, involving other dyes, additives and substrates, is under study in order to achieve a rational interpretation of these encouraging technical results.

Structure optimization in a series of thiadiazole disperse dyes using a chemometric approach

Structure optimization in a series of thiadiazolyl azo dyes to be used as disperse dyes for polyester fibres has been carried out by a chemometric approach based on experimental design in principal properties and PLS modelling. The thiadiazole nucleus confers a general excellent performance with respect to wet fastness. Light fastness depends on the substitution pattern. Three dyes with especially high fastness values have been identified.

Disperse and cationic dyes from aminophenyl-X-azolo-pyridines

Abstract A series of monoazo dyes was obtained by coupling diazotized aminophenyl-X-azolo-pyridines to N,N-diethylaniline. The dyes showed a great versatility towards different substrates such as polyamide, polyester, cellulose acetate and, after quaternization, polyacrylonitrile. In addition to the evaluation of parameters such as physical and spectroscopic constants, fastnesses on dyed fabrics, colour assessment and their correlation with structure, the dyes were also used in investigating the reactivity of the hetaryls. 1 H NMR was used to clarify the structure of the cationic dyes which, in the case of the imidazo-[4,5-c] isomers, proved to be imidazolium salts rather than the pyridinium salts previously observed for dyes containing an X-azolopyridine moiety.

Partial least-squares modelling of dye fastness to light

Abstract Several physicochemical properties ( 13 C-n.m.r., spectrophotometric, chromatographic, calorimetric) were measured for a series of 38 azo dyes in order to test the existence of relationships between one or more of these data sets and the fastness of the dyes on polyester fabric. The partial least-squares method was applied; it had previously proved useful in establishing structure/property relationships for the same dyes. It is shown that 13 C-n.m.r. data can be used successfully to predict dye fastness to light. These data are quickly and cheaply obtained with small amounts of compound.

Design of dyes of high technical properties for silk by a chemometric approach

A range of amines and coupling components were explored with the aim of identifying the best structures in a series of acid azo dyes for silk. The technique of the Experimental Design in Principal Properties was used for the selection of a small number of dyes to be synthesized and tested. Fastness data have been modelled as a function of the structure by the Partial Least Squares (PLS) method. The models established allowed the prediction of the fastness of new dyes of the series. Three violet dyes, one in the training set and two in the prediction set, with outstanding fastness performance were identified.

QSAR study of inclusion complexes of heterocyclic compounds with β-cyclodextrin

Abstract A QSAR study of the complexation of a series of unsubstituted heterocyclic compounds with β-cyclodextrin is reported. A training set of compounds was selected among eighteen commercially available heterocycles by a multivariate statistical design. The measured stability constants of the complexes were modelled as a function of the heterocycle structure by Partial Least Squares (PLS) method and the model developed used to predict the stability constants of other compounds of the series. Separate models for heterocyclic compounds containing nitrogen, alone or with a second heteroatom, and for compounds with oxygen or sulfur in the ring, are needed in order to have a satisfactory predictive ability.

Technical properties and photofading of disperse heterocyclic azo dyes

Abstract A series of heter acyclic azo dyes derived from aminophenyl-benzothiazoles and substituted dialkylanilines was prepared and tested on polyamide and polyester. The overall properties were satisfactory and compared favourably with related dyes previously described. Several correlations between structure and physical, spectroscopic (VIS and NMR) and fastness properties were found. An investigation of the photofading of the dyes on substrates as a function of time, checked with colourimetric techniques, proved a close time-dependent feature for colour parameters.

Quantitative relationships between chemical structure and technical properties of arylazoindole sulphonic acid dyes

Abstract A series of arylazoindole sulphonic acid dyes has been synthesised and their spectrophotometric properties have been determined. Their technical properties, such as lightfastness, fastness to washing and substantivity, on nylon and on wool, have been measured. The values obtained of each of these properties have been analysed by a modified Free-Wilson technique. Good correlations with substituent effects have been detained, demonstrating the validity of the additive model in the study of quantitative structure-activity relationships for this set of dyes. The quantification of substituent contributions makes it possible to point out the most active substituents as well as the most critical positions in order to improve the technical properties.