@article{williams_vacchi_santos_szymczyk_umbuzeiro_freeman_2022, title={Evaluation of the Toxicological and Color Properties of Anionic Hydrophobic Monoazo Dyes for Sustainable Human Hair Coloration}, volume={10}, ISSN={["2168-0485"]}, DOI={10.1021/acssuschemeng.1c05702}, abstractNote={The design of hair dyes having environmentally benign characteristics in addition to very good durability to washing and UV light is of importance to overcome the limitations of conventional permanent hair dyes in the marketplace. As a step toward meeting this vision, we synthesized anionic azo dyes having a built-in C4, C8, or C12 alkyl chain and evaluated their hair dyeing and toxicological properties. As anticipated, the dyes increased in hydrophobicity (SlogP) with the increase in alkyl chain length. Based on prior technology, it is known that certain anionic textile dyes possessing a C12 group exhibit high affinity for wool fibers during rigorous washing in the commercial milling process. In the present study, the dye containing the C8 chain displayed the greatest uptake and the most promise as a potential permanent hair dye. Further, dyes containing a C4 or C8 carbon chain were found to be nontoxic ≤100 mg L using the crustaceans Daphnia similis and Parhyale hawaiensis as test organisms. The dye containing a C12 carbon chain provided an EC50 of 57.4 mg L–1 using D. similis, but it was nontoxic ≤100 mg L–1 to P. hawaiensis. All dyes were nontoxic using the algae Raphidocelis subcapitata, and none of the dyes exhibited mutagenicity toward the strains used.}, number={8}, journal={ACS SUSTAINABLE CHEMISTRY & ENGINEERING}, author={Williams, Tova N. and Vacchi, Francine I. and Santos, Amanda and Szymczyk, Malgorzata and Umbuzeiro, Gisela de Aragao and Freeman, Harold S.}, year={2022}, month={Feb}, pages={2593–2601} }
 @article{ding_szymczyk_mehraban_lim_parrillo-chapman_el-shafei_freeman_2022, title={Molecular and excited state properties of photostable anthraquinone red and violet dyes for hydrophobic fibers}, volume={1248}, ISSN={["1872-8014"]}, DOI={10.1016/j.molstruc.2021.131349}, abstractNote={The molecular, spectroscopic, and excited state properties of synthetic dyes for fiber-based outdoor materials continue to be of commercial interest. Early developments in this area were reported in the 1980s, when the need for dyes for polyester (PET)-based automobile interiors gave rise to commercially viable nitrodiphenylamine yellow, anthraquinone red and blue, and azo red dyes. To augment that initial knowledge base, the present study involved the use of experimental and theoretical methods to help establish the molecular structures and excited state properties of some more recent dyes for producing photostable colors on PET fibers. Having completed the characterization of present-day scarlet, blue, and yellow disperse dyes for PET-based fibers used outdoors, our attention turned to commercially available red and violet dyes. In this regard, HPLC analysis showed that the red product was a mixture containing four components, while the violet product contained only one component. Results from 1H NMR, HRMS, and single crystal X-ray diffraction analyses indicated that the principal components were dyes having a 1-amino-4-hydroxyanthraquinone base structure. The presence of an –OH group alpha to an anthraquinone C=O moiety provides for intramolecular H-bonding and a subsequent opportunity for intramolecular proton transfer in the excited state – as a photostabilizing mechanism. Further, for both dyes, results from the analysis of Frontier HOMO and LUMO isosurfaces indicated strong HOMO-LUMO overlap without molecular gaps and were consistent with strong excited state energy dissipation in a non-destructive way.}, journal={JOURNAL OF MOLECULAR STRUCTURE}, author={Ding, Yi and Szymczyk, Malgorzata and Mehraban, Nahid and Lim, Jihye and Parrillo-Chapman, Lisa and El-Shafei, Ahmed and Freeman, Harold S.}, year={2022}, month={Jan} }
 @article{umbuzeiro_morales_vacchi_albuquerque_szymczyk_sui_vinueza_freeman_2021, title={A promising Ames battery for mutagenicity characterization of new dyes}, volume={62}, ISSN={["1098-2280"]}, url={http://www.scopus.com/inward/record.url?eid=2-s2.0-85097440491&partnerID=MN8TOARS}, DOI={10.1002/em.22417}, abstractNote={Abstract When testing new products, potential new products, or their impurities for genotoxicity in the Ames test, the quantity available for testing can be a limiting factor. This is the case for a dye repository of around 98,000 substances the Max Weaver Dye Library (MWDL). Mutagenicity data on dyes in the literature, although vast, in several cases is not reliable, compromising the performance of the in silico models. In this report, we propose a strategy for the generation of high‐quality mutagenicity data for dyes using a minimum amount of sample. We evaluated 15 dyes from different chemical classes selected from 150 representative dyes of the MWDL. The purity and molecular confirmation of each dye were determined, and the microplate agar protocol (MPA) was used. Dyes were tested at the limit of solubility in single and concentration‐response experiments using seven strains without and with metabolic activation except for anthraquinone dyes which were tested with eight strains. Six dyes were mutagenic. The most sensitive was YG1041, followed by TA97a > TA98 > TA100 = TA1538 > TA102. YG7108 as well as TA1537 did not detect any mutagenic response. We concluded that the MPA was successful in identifying the mutagenicity of dyes using less than 12.5 mg of sample. We propose that dyes should be tested in a tiered approach using YG1041 followed by TA97a, TA98, and TA100 in concentration‐response experiments. This work provides additional information on the dye mutagenicity database available in the literature.}, number={1}, journal={ENVIRONMENTAL AND MOLECULAR MUTAGENESIS}, author={Umbuzeiro, Gisela A. and Morales, Daniel A. and Vacchi, Francine I and Albuquerque, Anjaina F. and Szymczyk, Malgorzata and Sui, Xinyi and Vinueza, Nelson and Freeman, Harold S.}, year={2021}, month={Jan}, pages={52–65} }
 @article{williams_szymczyk_freeman_2021, title={In situ Chelation of Monoazo Dyes in Human Hair Keratin Fibers Using Environmentally Benign Metal Ions}, volume={4}, url={https://doi.org/10.1021/acsabm.1c00512}, DOI={10.1021/acsabm.1c00512}, abstractNote={The coloration of human hair keratin fibers has long involved the oxidative coupling of primarily aromatic amines and phenols inside the fibers with the aid of harsh agents such as H2O2 and NH4OH. Further, the traditional process has exposed millions of consumers and their hairstylists to toxic substances such as skin sensitizers. While alternative hair dyeing processes have been explored, they fail to be competitive with the traditional method, for reasons including impracticality and limited colors achievable. In the present study, we developed an approach to imparting color to human hair fibers that involves entrapping colorants inside hair fibers by forming chelated monoazo dyes in situ. Dyes employed were based on monoarylide, arylazopyrazolone, and arylazonaphthol families, which display yellow, orange, and magenta colors on dyed hair. The dyes were applied at 40 °C without the use of oxidants and alkali associated with current commercial hair dyes, with the best dye uptake observed when the arylazonaphthol dye was employed. The dyed hair fibers showed good durability to washing, and treatment of these fibers with Al3+ or Fe3+ ions at 40 °C led to the rapid in situ formation of 1:2 metal/dye structures. In addition, the dyed hair was soft, indicating that chelated dye occupies the interior of the fibers rather than the surface. Such an approach can be applied to the coloration of other materials, including textiles.}, number={8}, journal={ACS Applied Bio Materials}, publisher={American Chemical Society (ACS)}, author={Williams, Tova N. and Szymczyk, Malgorzata and Freeman, Harold S.}, year={2021}, month={Aug}, pages={6195–6202} }
 @article{ding_szymczyk_mehraban_lim_parrillo-chapman_el-shafei_freeman_2020, title={Molecular and excited state properties of photostable yellow disperse dyes}, volume={1207}, ISSN={["1872-8014"]}, url={http://www.scopus.com/inward/record.url?eid=2-s2.0-85078970244&partnerID=MN8TOARS}, DOI={10.1016/j.molstruc.2020.127815}, abstractNote={Abstract Textile dyes with high resistance to UV light induced fading on poly (ethylene terephthalate) (PET) fibers are important for textile substrates used in applications such as automobile interiors and outdoor furniture. Dye photostability influenced the development of dye structures for automobile fabrics dating back to the 1980s but the nature of currently used disperse dyes is less widely known. As part of a study designed to provide updates on this subject, the current investigation employed experimental and theoretical methods to determine the nature and properties of commercial dyes used to produce lightfast colors on PET fibers. Having completed the characterization of scarlet and blue disperse dyes for PET-based fabrics used outdoors, our attention turned to the characterization of commercially available lightfast yellow dyes. HPLC analysis showed that a pair of yellow products were mixtures containing three or four dyes, and the use of 1NMR, HRMS and single crystal X-ray diffraction analyses indicated that they were homologous azo–anthraquinone based dyes with or without a 1,8-bis(phenylthio)anthraquinone dye. Results from calculating Frontier HOMO and LUMO isosurfaces indicated strong HOMO/LUMO overlap, and the E0-0 for the homologous anthraquinone-based azo dyes was exactly the same (2.37 eV) which contributes to their photostability.}, journal={JOURNAL OF MOLECULAR STRUCTURE}, author={Ding, Yi and Szymczyk, Malgorzata and Mehraban, Nahid and Lim, Jihye and Parrillo-Chapman, Lisa and El-Shafei, Ahmed and Freeman, Harold S.}, year={2020}, month={May} }
 @article{ding_mehraban_szymczyk_parrillo-chapman_el-shafei_freeman_2019, title={Molecular and excited state properties of photostable anthraquinone blue dyes for hydrophobic fibers}, volume={1181}, ISSN={0022-2860}, url={http://dx.doi.org/10.1016/J.MOLSTRUC.2018.12.070}, DOI={10.1016/j.molstruc.2018.12.070}, abstractNote={Abstract Synthetic dyes having high photostability on hydrophobic fibers such as poly(ethylene terephthalate) (PET) are of interest for use on textile substrates for outdoor applications. While much is known about photostable dyes developed for PET in the 1980s, owing to their viability for use in automobile interiors, little has been published on currently viable photostable disperse dyes. As part of an effort to help fill this void and to facilitate future photostable disperse dye design, the present study involved the use of experimental measurements and modelling studies to help characterize the molecular structures of commercially viable dyes for producing photostable colors on PET fibers, beginning with a pair of blue dyes. With the aid of HR-MS, 500 MHz 1H NMR, and X-ray crystallography, it was established that the two dyes are structural isomers having 1,5-(OH)2-anthraquinone (AQ) and 1,8-(OH)2-AQ base structures. It is proposed that the photostability of these dyes arises from the presence of multiple OH/NH groups ortho to the AQ C O groups which enables them to dissipate excited state energy through intramolecular proton transfer. Further, using DFT-based molecular modelling studies, it was shown that the dye having the 1,5-(OH)2-AQ base structure has a lower ESOP than the isomeric dye having the 1,8-(OH)2-AQ base structure. Similarly, results from calculating Frontier HOMO and LUMO isosurfaces indicated that the LUMO lobes of the latter dye are larger, suggesting that this dye undergoes excitation faster than the 1,5-(OH)2-AQ isomer.}, journal={Journal of Molecular Structure}, publisher={Elsevier BV}, author={Ding, Yi and Mehraban, Nahid and Szymczyk, Malgorzata and Parrillo-Chapman, Lisa and El-Shafei, Ahmed and Freeman, Harold S.}, year={2019}, month={Apr}, pages={109–117} }
 @article{umbuzeiro_albuquerque_vacchi_szymczyk_sui_aalizadeh_ohe_thomaidis_vinueza_freeman_2019, title={Towards a reliable prediction of the aquatic toxicity of dyes}, volume={31}, ISSN={["2190-4715"]}, url={http://www.scopus.com/inward/record.url?eid=2-s2.0-85074502142&partnerID=MN8TOARS}, DOI={10.1186/s12302-019-0258-1}, abstractNote={Abstract Background The Max Weaver Dye Library (MWDL) from North Carolina State University is a repository of around 98,000 synthetic dyes. Historically, the uses for these dyes included the coloration of textiles, paper, packaging, cosmetic and household products. However, little is reported about their ecotoxicological properties. It is anticipated that prediction models could be used to help provide this type information. Thus, the purpose of this work was to determine whether a recently developed QSAR (quantitative structure–activity relationships) model, based on ACO-SVM techniques, would be suitable for this purpose. Results We selected a representative subset of the MWDL, composed of 15 dyes, for testing under controlled conditions. First, the molecular structure and purity of each dye was confirmed, followed by predictions of their solubility and pKa to set up the appropriate test conditions. Only ten of the 15 dyes showed acute toxicity in Daphnia, with EC 50 values ranging from 0.35 to 2.95 mg L −1 . These values were then used to determine the ability of the ACO-SVM model to predict the aquatic toxicity. In this regard, we observed a good prediction capacity for the 10 dyes, with 90% of deviations within one order of magnitude. The reasons for this outcome were probably the high quality of the experimental data, the consideration of solubility limitations, as well as the high purity and confirmed chemical structures of the tested dyes. We were not able to verify the ability of the model to predict the toxicity of the remaining 5 dyes, because it was not possible to determine their EC 50 . Conclusions We observed a good prediction capacity for the 10 of the 15 tested dyes of the MWDL, but more dyes should be tested to extend the existing training set with similar dyes, to obtain a reliable prediction model that is applicable to the full MWDL.}, number={1}, journal={ENVIRONMENTAL SCIENCES EUROPE}, author={Umbuzeiro, Gisela de A. and Albuquerque, Anjaina F. and Vacchi, Francine I and Szymczyk, Malgorzata and Sui, Xinyi and Aalizadeh, Reza and Ohe, Peter C. and Thomaidis, Nikolaos S. and Vinueza, Nelson R. and Freeman, Harold S.}, year={2019}, month={Dec} }
 @article{lim_szymczyk_mehraban_ding_parrillo-chapman_el-shafei_freeman_2018, title={Data from X-ray crystallographic analysis and DFT calculations on isomeric azo disperse dyes}, volume={21}, ISSN={["2352-3409"]}, url={http://www.scopus.com/inward/record.url?eid=2-s2.0-85055317185&partnerID=MN8TOARS}, DOI={10.1016/j.dib.2018.10.010}, abstractNote={X-ray crystallography and DFT calculations were used to characterize the molecular nature and excited state properties of isomeric photostable azo dyes for textile fibers undergoing extensive sunlight exposure. Structural data in CIF files arising from X-ray analysis are reported and the complete files are deposited with the Cambridge Crystallographic Data Centre as CCDC 1548989 (https://www.ccdc.cam.ac.uk/structures/Search?Ccdcid=1548989) and CCDC 1548990 (https://www.ccdc.cam.ac.uk/structures/Search?Ccdcid=1548990). Data from calculating the vertical electronic excitation of 20 excited states for each dye and from calculating excited state oxidation potential (ESOP) and Frontier HOMO/LUMO isosurfaces are also presented. This data is related to the article “Molecular and excited state properties of isomeric scarlet disperse dyes” (Lim et al., 2018) [1].}, journal={DATA IN BRIEF}, author={Lim, Jihye and Szymczyk, Malgorzata and Mehraban, Nahid and Ding, Yi and Parrillo-Chapman, Lisa and El-Shafei, Ahmed and Freeman, Harold S.}, year={2018}, month={Dec}, pages={675–683} }
 @article{sultana_liu_szymczyk_freeman_vinueza_2018, title={Dimerised heterobifunctional reactive dyes. Part 1: characterisation using quadrupole time-of-flight mass spectrometry}, volume={134}, ISSN={1472-3581}, url={http://dx.doi.org/10.1111/cote.12368}, DOI={10.1111/cote.12368}, abstractNote={As part of an approach to enhancing the efficiency of reactive dye adsorption on cellulosic fibres at low electrolyte levels, commercially available dyes were dimerised using hexamethylenediamine (HMDA) as a linking group. A key component of this work involved using high‐resolution mass spectrometry (HRMS) to characterise a group of polysulphonated heterobifunctional monochlorotriazine/vinyl sulphone reactive dyes (CI Reactive Yellow 176, CI Reactive Red 239, CI Reactive Blue 221, CI Reactive Red 194 and CI Reactive Blue 222) and their dimeric analogs. In this respect, dimeric dye ions of differently charged states were observed using HRMS‐negative electrospray ionisation in combination with quadrupole time‐of‐flight mass spectrometry. For example, HRMS showed that the HMDA‐linked reaction products were mixtures of the target (unhydrolysed) dimers, hydrolysed dimers, monoreacted products and hydrolysed unreacted dyes, with CI Reactive Yellow 176 and CI Reactive Red 194 producing the desired unhydrolysed dimers.}, number={6}, journal={Coloration Technology}, publisher={Wiley}, author={Sultana, Nadia and Liu, Yixin and Szymczyk, Malgorzata and Freeman, Harold S. and Vinueza, Nelson R.}, year={2018}, month={Aug}, pages={470–477} }
 @article{lim_szymczyk_mehraban_ding_parrillo-chapman_el-shafei_freeman_2018, title={Molecular and excited state properties of isomeric scarlet disperse dyes}, volume={1161}, ISSN={["1872-8014"]}, url={http://www.scopus.com/inward/record.url?eid=2-s2.0-85042332047&partnerID=MN8TOARS}, DOI={10.1016/j.molstruc.2018.02.028}, abstractNote={Abstract This work was part of an investigation aimed at characterizing the molecular and excited state properties of currently available disperse dyes developed to provide stability to extensive sunlight exposures when adsorbed on poly(ethylene terephthalate) (PET) fibers. Having completed the characterization of yellow, magenta, and cyan disperse dyes for PET-based fabrics used outdoors, our attention turned to the colors designed to enhance the color gamut of a standard 4-member (cyan/yellow/magenta/black) color set. The present study pertained specifically to the characterization of commercially available scarlet dyes. In this regard, HPLC analysis showed that a scarlet product used for PET coloration was mainly a 70/30 mixture of dyes, and the use of HRMS and single crystal X-ray diffraction analyses indicated that these two dyes were azo compounds derived from isomeric pyridine-based couplers which differed in the location of the primary amino ( NH2) and anilino ( NHPh) groups attached to the pyridine ring. One dye structure has the NHPh group para to the azo group (Sc2), while the other has that group in the ortho position (Sc3). The presence of either ortho substituent provides photostabilization through intramolecular H-bonding with the azo moiety. Further, results from molecular modeling studies showed that the lower excited state oxidation potential of Sc3 relative to that of Sc2 allows Sc3 to function as an energy quencher for the excited state of Sc2 – through thermodynamically favorable electron transfer.}, journal={JOURNAL OF MOLECULAR STRUCTURE}, author={Lim, Jihye and Szymczyk, Malgorzata and Mehraban, Nahid and Ding, Yi and Parrillo-Chapman, Lisa and El-Shafei, Ahmed and Freeman, Harold S.}, year={2018}, month={Jun}, pages={254–261} }
 @article{kuenemann_szymczyk_chen_sultana_hinks_freeman_williams_fourches_vinueza_2017, title={Weaver's historic accessible collection of synthetic dyes: a cheminformatics analysis}, volume={8}, ISSN={["2041-6539"]}, DOI={10.1039/c7sc00567a}, abstractNote={We present the Max Weaver Dye Library, a collection of ∼98 000 vials of custom-made and largely sparingly water-soluble dyes. Two years ago, the Eastman Chemical Company donated the library to North Carolina State University. This unique collection of chemicals, housed in the College of Textiles, also includes tens of thousands of fabric samples dyed using some of the library's compounds. Although the collection lies at the core of hundreds of patented inventions, the overwhelming majority of this chemical treasure trove has never been published or shared outside of a small group of scientists. Thus, the goal of this donation was to make this chemical collection, and associated data, available to interested parties in the research community. To date, we have digitized a subset of 2700 dyes which allowed us to start the constitutional and structural analysis of the collection using cheminformatics approaches. Herein, we open the discussion regarding the research opportunities offered by this unique library.}, number={6}, journal={CHEMICAL SCIENCE}, author={Kuenemann, Melaine A. and Szymczyk, Malgorzata and Chen, Yufei and Sultana, Nadia and Hinks, David and Freeman, Harold S. and Williams, Antony J. and Fourches, Denis and Vinueza, Nelson R.}, year={2017}, month={Jun}, pages={4334–4339} }
 @article{szymczyk_el-shafei_freeman_2007, title={Design, synthesis, and characterization of new iron-complexed azo dyes}, volume={72}, ISSN={0143-7208}, url={http://dx.doi.org/10.1016/j.dyepig.2005.07.009}, DOI={10.1016/j.dyepig.2005.07.009}, abstractNote={As part of a continuing study pertaining to the use of Fe as a substitute for metals such as Cr and Co in the design and synthesis of metal-complexed azo and formazan dyes, the synthesis of dye ligands containing ortho-trifluoroacetamido or mesylamido groups in the diazo components was undertaken. It was anticipated that these groups would mimic the acidity and metallizing properties of an ortho-OH group, thus producing new Fe-complexed dyes. The target ligands were synthesized in 4–5 steps and 80–91% yields from commercially available intermediates. 1H NMR was used to confirm the structures of the target dye ligands. The resultant azo and formazan systems readily formed 1:2 Fe-complexes when an ortho-NHSO2Me group was employed, while preparation of Fe-complexes from dye ligands having an ortho-NHCOCF3 group proved difficult, with mixtures of unmetallized dye, Fe-complex, and Fe hydroxide obtained despite variations in reaction conditions. Results of DFT calculations suggest that electron density at the N-22 atom was significantly diminished by the electron-withdrawing power of the CF3 moiety, inhibiting complex formation.}, number={1}, journal={Dyes and Pigments}, publisher={Elsevier BV}, author={Szymczyk, Malgorzata and El-Shafei, Ahmed and Freeman, Harold S.}, year={2007}, month={Jan}, pages={8–15} }