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• Changes of absorbances and melting points were not related to color differences. • Changes in solubilities and affinities were fundamental reason for color differences. • Degree of esterification had greatest effect on disperse red 167:1′s color difference. [Display omitted] The reason of color differences caused by different degree of esterification disperse dyes were investigated by disperse orange 30, disperse red 167:1, disperse blue 79:1 with different degree of esterification. The results showed that the changes of light absorbance abilities and melting points caused by ester groups had no obvious correlation with the color differences caused by ester groups. The changes in the solubilities and affinities caused by the ester groups were the fundamental reason for the changes in the dyeing properties of disperse orange 30, disperse red 167:1 and disperse blue 79:1. As a joint result of the decrease in solubilities and affinities, the dye sorption in polyethylene terephthalate of unesterified disperse orange 30, unesterified disperse red 167:1 and unesterified disperse blue 79:1 were reduced by 37.7%, 83.6% and 54.6%, respectively, compared with those of the corresponding completely esterified dyes. [ABSTRACT FROM AUTHOR]

Supercritical carbon dioxide (scCO 2) is commonly used as an excellent solvent in chemical reactions and dyeing fields because of its advantages. In this work, three coumarin and 1,8-naphthalimide fluorescent dyes (DAMC , NP-NH , and NP-dimethyl) were successfully constructed on the basis of the Au/titanium dioxide (Au/TiO 2) catalytic reduction of nitro in scCO 2 instead of SnCl 2 /hydrochloric acid solution, and their structures were confirmed correctly by mass spectrometry (MS) and nuclear magnetic resonance (NMR). The cleaner synthesis and dyeing polyester fabrics of coumarin derivative (DAMC) in the presence or absence of N-methyl-pyrrolidone (NMP) were first studied by employing stepwise and synchronous methods. All results for DAMC indicated that the synchronous synthesis and dyeing method is more beneficial. Here, the synchronous synthesis and dyeing polyester fabrics of 1,8-naphthalimide derivatives (NP–NH and NP-dimethyl) in scCO 2 were also investigated. Through the comprehensive analysis of color strength (K/S) value and fixation rate, the optimal temperatures and pressures of synthesis and dyeing for NP-NH and NP-dimethyl were obtained in the absence or presence of NMP. The dyed fabrics with NP-NH and NP-dimethyl exhibited yellow or yellowish-brown in daylight and bright fluorescent yellowish-green in ultraviolet light. All results showed that the clean production of fluorescent dyes (DAMC , NP-NH , and NP-dimethyl) can be realized by the hydrogenation of nitro with efficient Au/TiO 2 catalyst in scCO 2 , meanwhile, the synchronous synthesis and dyeing method was proposed for the synthesized dyes. The realization of synchronous synthesis and dyeing fabrics for fluorescent dyes in scCO 2 is an effective way to prevent environment pollution brought by the processes of synthesis and dyeing. Thus, the constructing and dyeing strategy of fluorescent dyes will be beneficial to the sustainable development of environment. In this study, three coumarin and 1,8-naphthalimide fluorescent dyes (DAMC , NP-NH , and NP-dimethyl) were successfully constructed on the basis of the Au/titanium dioxide (Au/TiO 2) catalytic reduction of nitro in scCO 2 , and their structures were confirmed correctly by mass spectrometry (MS) and nuclear magnetic resonance (NMR). The cleaner synthesis and dyeing polyester fabrics of coumarin derivative (DAMC) in the presence or absence of N-methyl-pyrrolidone (NMP) were first studied by employing stepwise and synchronous methods. All results for DAMC indicated that the synchronous synthesis and dyeing method is more beneficial. Here, the synchronous synthesis and dyeing polyester fabrics of 1,8-naphthalimide derivatives (NP–NH and NP-dimethyl) in scCO 2 were also investigated. Through the comprehensive analysis of color strength (K/S) value and fixation rate, the optimal temperatures and pressures of synthesis and dyeing for NP-NH and NP-dimethyl were obtained in the absence or presence of NMP. The dyed fabrics with NP-NH and NP-dimethyl exhibited yellow or yellowish-brown in daylight and bright fluorescent yellowish-green in ultraviolet light.Synopsis: The synchronous synthesis and dyeing polyester fabrics of coumarin and 1,8-naphthalimide dyes in scCO 2 were also investigated. [Display omitted] • Three coumarin and 1,8-naphthalimide fluorescent dyes were constructed in scCO 2 media. • The synchronous synthesis and dyeing method was proposed for the synthesized dyes in scCO 2. • The constructing and dyeing strategy of fluorescent dyes is beneficial for the sustainable development of environment. [ABSTRACT FROM AUTHOR]

Technology of supercritical carbon dioxide (scCO 2) dyeing has been used in dyeing synthetic and natural fibers. It is important to understand the scCO 2 dyeing mechanism owing to the possibility of using this knowledge to design dyes that are suitable for scCO 2 dyeing. Here, using the N-site and 4-site modification of 1,8-naphthalimide matrix, six fluorescent dyes (1 , 2 , 3 , 4 , 5 , and 6) with fluorescent properties were synthesized; dyeing performance and fluorescent images indicate that all the synthesized dyes can be utilized for scCO 2 dyeing wool fibers. Therefore, the dyed wool fibers possess not only conventional dyeing characteristics but also luminescent properties. Especially, the dyed wool fibers with solid free fluorescent dye 2 exhibit strong yellow-green fluorescence. Owing to the lack of proper fixation process, the fixation rate of these six fluorescent dyes on wool fibers was not relatively high. Thus, the dye 7 with an active group N-hydroxysuccinimide (NHS) was synthesized to improve the binding force between dyes and wool fibers and it can react with the –NH 2 group in wools, which results in that the fixation rate of the synthesized dye 7 reaches approximately 91% through chemical combination. Mass spectra prove that the byproduct of 7 reacting with the amino group of wool fibers is not corrosive to dyeing equipment, which realizes the eco-friendly fluorescent dyeing of wool fibers in scCO 2. Our results proved that the fluorescent dyes with conjugated system can overcome the problem of fluorescence quenching in natural fibers. Meanwhile, our strategy of constructing fluorescent dyes and the proposed dyeing mechanism will be helpful to develop reactive disperse dyes that are suitable for scCO 2 dyeing. [Display omitted] • The dyed wool fibers with solid free fluorescent dye 2 showed strong yellow-green fluorescence. • Photophysical properties and dyeing mechanism of dyes suitable for the scCO 2 dyeing wool fibers were investigated. • The fixation rate of new reactive disperse dye 7 reached approximately 91% through chemical combination. [ABSTRACT FROM AUTHOR]