@article{marshburn_ashley_curtin_sultana_liu_vinueza_ison_jakubikova_2021, title={Are all charge-transfer parameters created equally? A study of functional dependence and excited-state charge-transfer quantification across two dye families}, volume={8}, ISSN={["1463-9084"]}, url={https://doi.org/10.1039/D1CP03383B}, DOI={10.1039/d1cp03383b}, abstractNote={Small molecule organic dyes have many potential uses in medicine, textiles, forensics, and light-harvesting technology. Being able to computationally predict the spectroscopic properties of these dyes could greatly expedite screening efforts, saving time and materials. Time-dependent density functional theory (TD-DFT) has been shown to be a good tool for this in many instances, but characterizing electronic excitations with charge-transfer (CT) character has historically been challenging and can be highly sensitive to the chosen exchange-correlation functional. Here we present a combined experimental and computational study of the excited-state electronic structure of twenty organic dyes obtained from the Max Weaver Dye Library at NCSU. Results of UV-vis spectra calculations on these dyes with six different exchange-correlation functionals, BP86, B3LYP, PBE0, M06, BH and HLYP, and CAM-B3LYP, were compared against their measured UV-vis spectra. It was found that hybrid functionals with modest amounts (20-30%) of included Hartree-Fock exchange are the most effective at matching the experimentally determined λmax. The interplay between the observed error, the functional chosen, and the degree of CT was analyzed by quantifying the CT character of λmax using four orbital and density-based metrics, Λ, Δr, SC and DCT, as well as the change in the dipole moment, Δμ. The results showed that the relationship between CT character and the functional dependence of error is not straightforward, with the observed behavior being dependent both on how CT was quantified and the functional groups present in the molecules themselves. It is concluded that this may be a result of the examined excitations having intermediate CT character. Ultimately it was found that the nature of the molecular "family" influenced how a given functional behaved as a function of CT character, with only two of the examined CT quantification methods, Δr and DCT, showing consistent behavior between the different molecular families. This suggests that further work needs to be done to ensure that currently used CT quantification methods show the same general trends across large sets of multiple dye families.}, journal={PHYSICAL CHEMISTRY CHEMICAL PHYSICS}, publisher={Royal Society of Chemistry (RSC)}, author={Marshburn, Richard Drew and Ashley, Daniel C. and Curtin, Gregory M. and Sultana, Nadia and Liu, Chang and Vinueza, Nelson R. and Ison, Elon A. and Jakubikova, Elena}, year={2021}, month={Aug} }
 @article{sultana_williams_ankeny_vinueza_2019, title={Degradation studies of CI Reactive Blue 19 on biodegraded cellulosic fabrics via liquid chromatography-photodiode array detection coupled to high resolution mass spectrometry}, volume={135}, ISSN={["1478-4408"]}, DOI={10.1111/cote.12440}, abstractNote={Abstract When textile substrates biodegrade in landfills, the fate of textile colorants is unknown, and potentially poses an ecotoxic threat. In this study, we developed a systematic analytical method to evaluate the biodegradation of reactive dyes, the most common class of dye applied to cotton fabrics. The cotton fabrics were dyed with CI Reactive Blue 19 and biodegraded in soil in a laboratory‐controlled environment over intervals of 45 and 90 days. A dye isolation method using a low concentration of alkali (0.15% sodium hydroxide) was developed and applied (80°C for 1 hour) to isolate intact and degraded dye from the fabric samples. To quantify the intact dye isolated from the fabric samples, a quantification method was then developed using liquid chromatography‐photodiode array detection. The quantification method provided excellent linearity ( R 2 = 0.9997 ± 0.0002), accuracy (% error = −2% ± 4), precision (% coefficient of variation = 2% ± 4) and sensitivity (lower limit of quantification = 0.4 ± 0.2 µg/mL) for concentrations ranging from 1 to 50 µg/mL. After validation, the method was applied and showed a reduction of dye in biodegraded samples (after 45 and 90 days) compared with undegraded control samples (0 days). To characterise the isolated dye degradation product, quadrupole time‐of‐flight tandem mass spectrometry was utilised. Analysis showed that the degradation product was formed by losing a group from the intact hydrolysed form of the dye, creating a more hydrophobic degradation product compared with the intact hydrolysed form of dye.}, number={6}, journal={COLORATION TECHNOLOGY}, author={Sultana, Nadia and Williams, Kelsey and Ankeny, Mary and Vinueza, Nelson R.}, year={2019}, month={Dec}, pages={475–483} }
 @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{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={The Max Weaver Dye Library is presented to the scientific community with a cheminformatics approach to enhance research opportunities with this unique collection of ∼98 000 vials of custom-made dyes.}, 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} }