The application of stimuli-responsive molecules in textiles is an important field due to its potential in
various areas of flexible sensing technology. In particular, pH plays an important role in nature, humans,
and several processes. The pH of body fluids is one of the best indicators of disturbed health conditions.
Thus, the development of textiles with halochromic properties has been increasingly attractive to display
in real-time pH variations. Wool is one of the most important natural fibres because of its warmth and
comfort. However, the dyeing process is costly and high energy-consuming. In this work, the
halochromic properties under different buffers (acetate, phosphate, Britton-Robinson, artificial sweat,
and artificial wound exudate) of a previously synthesized 5-aminoimidazole-4-carboxamidrazone were
studied. Moreover, the first attempt to dye a wool knitted fabric with this molecule at a low temperature
was performed. The developed material showed interesting halochromic properties (colourless in acidic
pH and blue colour in the alkaline pH), even using artificial body fluids.This work was funded by European Regional Development Fund through the Operational
Competitiveness Program and the National Foundation for Science and Technology of Portugal (FCT)
under the projects UID/CTM/00264/2021, UID/QUI/00686/2020, MEDCOR PTDC/CTMTEX/1213/2020 and Ph.D. scholarship SFRH/BD/137668/2018

Cerqueira, Fátima

Dantas, Daniela Filipa Costa

Dias, Alice

Pinto, Eugénia

Remião, Fernando

Ribeiro, Ana Isabel Ferreira

Silva, Renata

Zille, Andrea

English

The application of stimuli-responsive molecules in textiles is an important field due to its potential in
various areas of flexible sensing technology. In particular, pH plays an important role in nature, humans,
and several processes. The pH of body fluids is one of the best indicators of disturbed health conditions.
Thus, the development of textiles with halochromic properties has been increasingly attractive to display
in real-time pH variations. Wool is one of the most important natural fibres because of its warmth and
comfort. However, the dyeing process is costly and high energy-consuming. In this work, the
halochromic properties under different buffers (acetate, phosphate, Britton-Robinson, artificial sweat,
and artificial wound exudate) of a previously synthesized 5-aminoimidazole-4-carboxamidrazone were
studied. Moreover, the first attempt to dye a wool knitted fabric with this molecule at a low temperature
was performed. The developed material showed interesting halochromic properties (colourless in acidic
pH and blue colour in the alkaline pH), even using artificial body fluids.This work was funded by European Regional Development Fund through the Operational Competitiveness Program and the National Foundation for Science and Technology of Portugal (FCT)
under the projects UID/CTM/00264/2021, UID/QUI/00686/2020, MEDCOR PTDC/CTMTEX/1213/2020 and Ph.D. scholarship SFRH/BD/137668/2018

Universidade do Minho: RepositoriUM

21st World Textile Conference   AUTEX 2022    Passion for Innovation  June 7-10, 2022, Lodz, Poland DOI: 10.34658/9788366741751.126HALOCHROMIC PROPERTIES OF A 5-AMINOIMIDAZOLE-4-CARBOXAMIDRAZONE AND ITS APPLICATION TO WOOL Ana Isabel Ribeiro1     , Daniela Dantas2     , Renata Silva3     , Fernando Remião3     , Eugénia Pinto4,5     , Fátima Cerqueira4,6,7     , Alice Dias2     , Andrea Zille1(*)  ABSTRACT The application of stimuli-responsive molecules in textiles is an important field due to its potential in various areas of flexible sensing technology. In particular, pH plays an important role in nature, humans, and several processes. The pH of body fluids is one of the best indicators of disturbed health conditions. Thus, the development of textiles with halochromic properties has been increasingly attractive to display in real-time pH variations. Wool is one of the most important natural fibres because of its warmth and comfort. However, the dyeing process is costly and high energy-consuming. In this work, the halochromic properties under different buffers (acetate, phosphate, Britton-Robinson, artificial sweat, and artificial wound exudate) of a previously synthesized 5-aminoimidazole-4-carboxamidrazone were studied. Moreover, the first attempt to dye a wool knitted fabric with this molecule at a low temperature was performed. The developed material showed interesting halochromic properties (colourless in acidic pH and blue colour in the alkaline pH), even using artificial body fluids.  KEYWORDS pH-responsive textiles, dyes, wool. INTRODUCTION Chromic molecules present a visual colour change when exposed to external stimuli and have received considerable attention for smart materials applications [1]. pH plays an important role in the human body, where several pH-dependent processes and reactions occur. Thus, controlling the pH of body fluids can be a suitable strategy to detect health problems (e.g. the measurement of the pH of sweat is useful to detect skin diseases, and the alkaline pH of wounds indicates infection and delayed healing). © 2022 by the authors. This article is an open access article distributed under the terms and conditions of the Creative Commons Attribution (CC-BY) license (http://creativecommons.org/licenses/by/4.0/) 1 Centre for Textile Science and Technology (2C2T), Departamento de Engenharia Têxtil,  Universidade do Minho, Campus de Azurém, 4800-058 Guimarães, Portugal 2 Centre of Chemistry of University of Minho (CQ-UM), Departamento de Química,  Universidade do Minho, Campus de Gualtar, 4710-057 Braga, Portugal 3 UCIBIO - Applied Molecular Biosciences Unit, REQUIMTE, Laboratory of Toxicology, Departmentof Biological Sciences, Faculty of Pharmacy, University of Porto, Porto, Portugal 4 Interdisciplinary Centre of Marine and Environmental Research (CIIMAR), University of Porto, 4450-208 Matosinhos, Portugal 5 Laboratory of Microbiology, Biological Sciences Department, Faculty of Pharmacy, University of Porto,4050-313 Porto, Portugal  6 Molecular Oncology and Viral Pathology Group, Research Center of IPO Porto (CI-IPOP) / RISE@CI-IPOP (Health Research Network), Portuguese Oncology Institute of Porto (IPO Porto) / Porto Comprehensive Cancer Center (Porto.CCC), Rua Dr. António Bernardino de Almeida, Porto, 4200-072, Portugal 7 FP-ENAS Research Unit, UFP Energy, Environment and Health Research Unit, CEBIMED, Biomedical Research Centre, Fernando Pessoa University, Praça 9 de Abril, 349, 4249-004 Porto, Portugal, and Faculty of Health Sciences, Fernando Pessoa University, Rua Carlos da Maia, 296, 4200-150 Porto, Portugal (*) Email: azille@2c2t.uminho.pt AUTEX 2022 Conference Proceedings         978-83-66741-75-1   © Lodz University of Technology, 2022 21st World Textile Conference   AUTEX 2022    Passion for Innovation  June 7-10, 2022, Lodz, Poland 596 Behind all the techniques developed for measuring the pH, the colour change remains one of the most cost-effective methods for real-time monitoring of the pH [2,3]. Thus, the development of new materials with halochromic properties has been increasingly attractive [4]. Amidrazones have been widely described due to their applications in many fields of chemistry, particularly in the synthesis of azo precursors [5,6]. These compounds are susceptible to oxidation and some of them have a very low oxidation potential [7].  Wool is one of the most popular natural fibres due to its natural properties such as warmth and comfort. Nevertheless, its dyeing process is costly and energy-consuming since it is usually performed at boiling or near-boiling temperature. Thus, the low-temperature dyeing of wool without agents is an urgent need [8].  In this work, the halochromic properties of a previously 5-aminoimidazole-4-carboxamidrazone synthesized by our research group were studied under different solutions from pH 3 to 12 using acetate, phosphate, Britton-Robinson, artificial sweat, and artificial wound exudate buffers. Then, the first attempt to dye wool with this amidrazone at a low temperature (40ºC) by exhaustion was performed. The solutions and the colour coordinates of the fabrics were measured by UV–vis spectrophotometry. MATERIALS AND METHODS 1. MaterialsCommercial wool jersey fabric with a weight per unit area of 160 gm-2 was used in this work. First, the fabric was washed using a solution of 1.0 gL-1 of a non-ionic detergent at 60 ºC for 60 minutes, rinsed with distilled water and dried. All reagents were purchased from Sigma-Aldrich without any purification. 2. Synthesis of the (Z)-5 amino-1-(4-methoxyphenyl)-N'-phenyl-1H-imidazole-4-carbohydrazonamide The amidrazone was prepared according to a previous method developed by the research group with slight differences [9]. To a 25 mL flask containing 2.0 g of 5-amino-1-(4-methoxyphenyl)-1H-imidazole-4-carbimidoyl cyanide (8.3 mmol) and 10 L of acetic acid in ethanol (8 mL) was added 1.25 mL of phenylhydrazine (12.5 mmol), under nitrogen atmosphere. The suspension was placed under magnetic stirring at a temperature of 8 °C for 17 hours. The compound was obtained in 94% yield (2.5 g; 7.8 mmol). The purity of this compound was proved by NMR (1H) and elemental analysis. The NMR spectra was performed at room temperature on a Bruker Avance 3400 (1H: 400 MHz). The data are reported by chemical shifts (ppm), multiplicity (s -singlet, brs - broad singlet d - doublet, t - triplet, dd - doublet of doublets or m - multiplet), the coupling constants (J) in hertz (Hz) and integration. Elemental analyses were performed on a LECO CHNS-932 instrument (University of Minho). 1H RMN (400 MHz, DMSO-d6): δ 3.81 (s, 3H), 5.57 (brs, 2H), 5.77 (brs, 2H), 6.59 (t, J= 8.0 Hz, 1H), 6.84 (d, J= 7.9 Hz, 2H), 7.11 (t, J= 7.9 Hz, 4H), 7.31 (s, 1H), 7.44 (d, J= 8.7 Hz, 2H), 7.92 (s, 1H); Anal. calc. for C17H18N6O: C, 63.34; H, 5.63; N, 26.07; found: C, 63.41; H, 5.62; N, 25.94. 3. Halochromic properties under different buffer solutionsUV-vis spectrophotometry (Shimadzu, UV-1800) was used to measure the absorbance spectra of the amidrazone under different buffer solutions with a standard quartz cuvette. The absorbance was measured in Britton-Robinson buffer (from pH 3 to 12), acetic acid-sodium acetate buffer (from pH 4 to 6), sodium phosphate buffer (from pH 6 to 8), artificial sweat (pH 4.3, 5.5, 8.0 and 6.5) and artificial wound exudate (pH 7.4). A starting solution of amidrazone (256 mg.L-1) was prepared and diluted in 50% (v/v) with the corresponding buffer. A dilution only with water instead buffers was used as control. 21st World Textile Conference   AUTEX 2022    Passion for Innovation  June 7-10, 2022, Lodz, Poland 597 The colour strength of the wool samples was studied using a UV-2600, UV–vis spectrophotometer manufactured by SHIMADZU, using a D65 illuminant in the range from 400 to 800 nm. The colouring effects in CIE L* (lightness), a* (yellowness–blueness), and b* (redness–greenness) space were calculated using RGB values. The transmittance was measured (from 280 to 400 nm) and the Ultraviolet Protection Factor (UPF) was estimated according to the AATCC test method 183-2020. RESULTS AND DISCUSSION Wool knitted fabric was functionalized with (Z)-5-amino-1-(4-methoxyphenyl)-N'-phenyl-1H-imidazole-4-carbohydrazonamide previously synthesized by the research group [9]. This compound proved to be easily oxidized in contact with air and motivated the study of the colour under different buffer solutions (Britton-Robinson, acetate and phosphate). Moreover, artificial body fluids were also tested (artificial sweat and wound exudate). The UV-vis spectra of the solutions showed the emergence of a light pink colour under acidic conditions and a strong blue colour under neutral or slightly alkaline pH for Britton-Robinson and phosphate buffer (Figure 1-a). Only one exception was found using the artificial sweat at pH 7. In this case, a pink colour emerged, similarly to the acidic conditions, but more intense (Figure 1-a). The UV-vis spectra showed the appearance of an intense band around 595 nm with neutral or alkaline pH using the Britton-Robinson and phosphate buffer (Figures 1-b and c). Using the artificial sweat solutions from acidic to neutral pH, the band at 507 nm become more intense when the pH is increased. Under artificial sweat at pH 8 and artificial wound exudate, the band at 595 nm emerged again (Figure 1-d). Figure 1. Colour changing of the amidrazone (Z)-5 amino-1-(4-methoxyphenyl)-N'-phenyl-1H-imidazole-4-carbohydrazonamide under the initial solution (IS) without buffers, Briton-Robinson buffer (BR), acetate buffer (A), phosphate buffer (P), artificial sweat (S) and artificial exudate (E) (a) and corresponding UV-vis spectra (b, c and d). Then, the amidrazone was used to dye a wool knitted fabric with solutions obtained with Britton-Robinson buffers at pH 5 and 8 by exhaustion at 40ºC. The colour of the wool samples was assessed in the CIE L* (lightness), a* (redness-greenness), and b* (yellowness-blueness) space (Figures 2-a and b). The colouration of the wool fabric changed from colourless, when acidic pH was used (Britton-Robinson buffer at pH 5 and the control initial solution (pH 3)), to blue when the alkaline buffer was used (Britton-Robinson buffer at pH 8) (Figure 2). The UPF of the samples was calculated and compared with a control sample without amidrazone. The results showed that the functionalization increased the UPF from 15 (untreated wool) to 17-21 (wool dyed with amidrazone) (Figure 2-c). The best result was obtained in the sample prepared in alkaline conditions. 4. Measurement of the colour of the wool samples21st World Textile Conference   AUTEX 2022    Passion for Innovation  June 7-10, 2022, Lodz, Poland 598 Figure 2. Colour coordinates of the wool samples (L* - lightness values, a* - yellowness-blueness and b* - redness-greenness) functionalized within amidrazone using the initial solution without buffers (IS) and using the Britton-Robinson buffers at pH 5 (BR5) and 8 (BR8). CONCLUSION The amidrazone (Z)-5-amino-1-(4-methoxyphenyl)-N'-phenyl-1H-imidazole-4-carbohydrazonamide was successfully applied on wool knitted fabric and showed interesting halochromic properties in acidic and alkaline conditions. Under acidic conditions the wool sample remained uncoloured and in alkaline conditions the colour changed to blue. In addition, the exhaustion process displayed good results at low temperature (40ºC). The functionalization also increased the UPF value of the wool from good to very good, according to AATCC 183-2020. This compound present high potential to be used as halochromic dyes for wool in functional textiles for sports, healthcare and sensors. ACKNOWLEDGMENT This work was funded by European Regional Development Fund through the Operational Competitiveness Program and the National Foundation for Science and Technology of Portugal (FCT) under the projects UID/CTM/00264/2021, UID/QUI/00686/2020, MEDCOR PTDC/CTM-TEX/1213/2020 and Ph.D. scholarship SFRH/BD/137668/2018. REFERENCES [1] Koga H., Nogi M., Isogai, A., Ionic Liquid Mediated Dispersion and Support of Functional Molecules on Cellulose Fibers for Stimuli-Responsive Chromic Paper Devices, ACS Applied Materials & Interfaces 2017, no 9(46), pp. 40914–40920. [2] Pan N., Qin J., Feng P., Li Z., Song B., Color-changing smart fibrous materials for naked eye real-time monitoring of wound pH, Journal of Materials Chemistry B 2019, no 7(16), pp. 2626–2633. [3] Zhang W., Liu X., Lin Y., Ma L., Kong L., Min G., Liu X.Y., Palladium nanoparticles/wool keratin-assisted carbon composite-modified flexible and disposable electrochemical solid-state pH sensor, Chinese Physics B 2022), vol. 31, no 2. [4] Proksch E., pH in nature, humans and skin, The Journal of Dermatology, vol. 45, no 9, pp. 1044–1052. [5] Mazur L., Sączewski J., Jarzembska K.N., Szwarc-Karabyka K., Paprocka R.,  Modzelewska-Banachiewicz B., Synthesis, structural characterization and reactivity of new trisubstitutedN1-acylamidrazones: solid state and solution studies, CrystEngComm 2018, vol. 20, no 29, pp. 4179–4193. [6] US3933493A. Sumitani, H., Ohyama, Y., Amidrazones as dye components and developer scavengers in diffusion transfer materials and processes. Mitsubishi Paper Mills. United States. 1976. 21st World Textile Conference   AUTEX 2022    Passion for Innovation  June 7-10, 2022, Lodz, Poland 599 [7] Krauth F., Friedemann R., Rüttinger H.H., Frohberg P., Open-chain and cyclic amidrazones forming persistent radicals. An electrochemical and quantum chemical study, Arkivoc 2009, no 7, pp. 150–164. [8] Sun J., Wang H., Zheng C.,  Wang G., Synthesis of some surfactant-type acid dyes and their low-temperature dyeing properties on wool fiber, Journal of Cleaner Production 2019, vol. 218, pp. 284–293. [9] Ribeiro A.I., Gabriel C., Cerqueira F., Maia M., Pinto E., Sousa J.C., Medeiros R., Proença M.F., Dias A.M., Synthesis and antimicrobial activity of novel 5-aminoimidazole-4- carboxamidrazones, Bioorganic & Medicinal Chemistry Letters 2014, vol. 24, no 19, pp. 4699–4702. 

Halochromic properties of a 5-aminoimidazole-4-carboxamidrazone and its application to wool

This work was funded by European Regional Development Fund through the
Operational Competitiveness Program and the National Foundation for Science and
Technology of Portugal (FCT) under the projects UID/CTM/00264/2021,
UID/QUI/00686/2020, MEDCOR PTDC/CTM-TEX/1213/2020 and Ph.D. scholarship
SFRH/BD/137668/201

HALOCHROMIC PROPERTIES OF A 5-AMINOIMIDAZOLE-4-CARBOXAMIDRAZONE AND ITS APPLICATION TO WOOLAna Isabel Ribeiro*, Daniela Dantas, Renata Silva, Fernando Remião, Fátima Cerqueira, Eugénia Pinto, Alice Dias, Andrea Zille0*afr@2c2t.uminho.pt1IntroductionGlobal fiber production (2021)Source: Textile Exchange websitePlant fibers 29.9%• Other plant-based 5.9%• Cotton 24.2%Animal fibers 1.6%• Wool-sheep 1.0%• Other wool 0.05%• Down 0.5%• Silk 0.1%Synthetic fibers 62.0%• Polyester 52.0%• Polyamide 5%• Polypropylene 2.7%• Acrylics 1.6%• Elastane 1.0%Manmade cellulosic fibers 5.9%• Viscose 4.7%• Acetate 0.8%• Lyocell 0.3%• Modal 0.2%• Cupro 0.01%2IntroductionMarket size of Wool by region (2021)CAGR4.8%2022-2027Source: Mordor Intelligence website3IntroductionWool properties and BenefitsSource: Woolmark website100% natural 100% biodegradable 100% renewableWrinkle resistant Naturally breathable Warm and cool Odour resistantEasy to care for Soft on skin Innovative Stain resistantNaturally elastic Fire resistant Reusable and recyclable UV resistant4IntroductionSource: Handbook of Natural Fibres, Wool fibres, Elsevier, 2020SportsMedical Automotive and AviationArchitecture and Design Protective ApparelApplications of Wool5IntroductionFunctional dyes§ Combination of both conventional textile dyeing and functional finishesUV-Protective Antimicrobial Water Repellent Moth Repellent 6IntroductionSmart dyes - Chromism§ Chromism is a change in color caused by external factorsPhotochromismThermochromismElectrochromismSolvatochromismIonochromismHalochromism7IntroductionHalochromism§ pH plays an important role in the human body§ The colour change remains one of the most cost-effective methods for real-time monitoring ofthe pH7.0 8.55.5Wound pH InfectionHealingpH of Sweat to Detect Skin DiseasesIrritant contact dermatitis, atopic dermatitis, ichthyosis, acne vulgaris and Candida albicans infections8Antimicrobial action against:Candida albicansCandida kruseiCandida parapsilosisCryptococcus neoformansIntroductionHistamineImmune response and neurotransmitter KetoconazoleAntifungalMetronidazoleAntibioticImidazoleAmidrazoneNN NH2RH2NNNHNN NH2RHNNNOxidizingAgentAmIz AzoIza, R=Ar(p)OMeb, R=Mea, R=Ar(p)OMeb, R=MeAgNPsSonication10’NN NH2RHNNNNN NH2RH2NNNHAmIz + AgNPs AzoIz + AgNPs§ Extensively used as intermediates of compoundswith biological activities due to its high reactivity[O]NNNH2NNHNNNHNNNH2NH2 O NHRRNNNH2NNNHRRN§ Important component of various natural molecules§ Extensive pharmacological potentialAzo Group9Objective and ProcedureThe halochromic properties of a 5-aminoimidazole-4-carboxamidrazone were studied, and the firstattempt to dye wool with this amidrazone at a low temperature was performed.1. Synthesis of the amidrazone• FTIR• 1H NMR2. Buffered solutions from pH 3 to 12- acetate, - phosphate, - Britton-Robinson, - Artificial sweat- artificial wound exudate  • UV-Vis3. Dyeing of wool by exhaustion at 40°C under acidic and alkaline pH• Color coordinates• UPF10ResultsSynthesis of the amidrazone – FTIR and 1H RMNNNR1NH2HNH2N CNCNH2NTEOFDAMNNH OEtCNCNH2N1NH NHR1CNCNH2N2NH2R13NNR1NH2NH2NCNBase4NNR1NH2NHN5·HNO3NNR1NH2NHN5AgNO3Base·HNO3N N NH10NNR1NH2NH2NNHNRRO2NNR1NHNH2NNNRRUnknown XO2NNR1NHNH2NNNRRUnknown X677NH2NHR2R2R2R2R2R2R2NNR1NH2NNH2NHNNH2NNN NH2R1O2O2NNR1NHNNH2NNNH2NNN NH2R1NNR1NHNNH2NNNH2NNN NH2R1899HNRRO2HNRR4R2NNNNHNH2NNR1 RRHNRRNNR1NH2HNH2N CNCNH2NTEOFDAMNNH OEtCNCNH2N1NH NHR1CNCNH2N2NH2R13NNR1NH2NH2NCNBase4NNR1NH2NHN5·HNO3NNR1NH2NHN5AgNO3Base·HNO3N N NH10NNR1NH2NH2NNHNRRO2NNR1NHNH2NNNRRUnknown XO2NNR1NHNH2NNNRRUnknown X677NH2NHR2R2R2R2R2R2R2NNR1NH2NNH2NHNNH2NNN NH2R1O2O2NNR1NHNNH2NNNH2NNN NH2R1NNR1NHNNH2NNNH2NNN NH2R1899HNRRO2HNRR4R2NNNNHNH2NNR1 RRHNRRNNR1H2HNH2N CNCNH2NTEOFDAMNNH OEtCNCNH2N1NH NHR1CNCNH22NH2R13NNR1NH2NH2NCNBase4NNR1NH2NHN5·HNO3125AgNO3Base·HNO3N NH10NNR1NH2NH2NNHNRRO2NNR1NHNH2NNRRUnknown XO2NNR1NHNH2NNNRRUnknown X677NH2NHR2R22R2R2R2R2NNR1NH2NNH2NHNNH2NNN NH2R1O2O2NNR1NHNNH2NNNH2NNN NH2R1NNR1NHNNH2NNNH2NNN NH2R1899HNRRO2HNRR4R2NNNNHNH2NNR1 RRHNRRNNR1NH2HNH2N CNCNH2NTEOFDAMNNH OEtCNCNH2N1NH NHR1CNCNH2N2NH2R13NNR1NH2NH2NCNBase4NNR1NH2NHN5·HNO3NNR1NH2NHN5AgNO3Base·HNO3N N NH10NNR1NH2NH2NNHNRRO2NNR1NHNH2NNNRRUnknown XO2NNR1NHNH2NNNRRUnknown X677NH2NHR2R2R2R2R2R2R2NNR1NH2NNH2NHNNH2NNN NH2R1O2O2NNR1NHNNH2NNNH2NNN NH2R1NNR1NHNNH2NNNH2NNN NH2R1899HNRRO2HNRR4R2NNNNHNH2NNR1 RRHNRRh =94%7.13 (s, 1H)5.57 (brs, 2H)5.77 (brs, 2H) 7.92 (brs, 1H)6.84 (d, 2H)7.11 (t, 2H)6.59 (t, 1H)3.81 (s, 3H)7.31 (d, 2H)7.44 (d, 2H)NH2 C=N C-N/C-O11ResultsBuffered solutions from pH 3 to 12 – UV-Vis12ResultsDyeing of wool by exhaustion at 40° C under acidic and alkaline pH√13Conclusion and Prospective work• The amidrazone was successfully applied on wool knitted fabric and showed interesting halochromic properties in acidic and alkaline conditions. • The exhaustion process displayed good results at low temperature (40 ° C). • The functionalization also increased the UPF value of the wool from good to very good. • This compound present high potential to be used as halochromic dyes for wool in functional textiles for sports, healthcare and sensors.• Fastness tests• Reversibility evaluation • Mechanism of dyeing process• Antimicrobial action of the fabrics against bacteria and fungi• Cytotoxicity tests14This work was funded by European Regional Development Fund through theOperational Competitiveness Program and the National Foundation for Science andTechnology of Portugal (FCT) under the projects UID/CTM/00264/2021,UID/QUI/00686/2020, MEDCOR PTDC/CTM-TEX/1213/2020 and Ph.D. scholarshipSFRH/BD/137668/2018.AcknowledgmentsGuimarães - PortugalHALOCHROMIC PROPERTIES OF A 5-AMINOIMIDAZOLE-4-CARBOXAMIDRAZONE AND ITS APPLICATION TO WOOLAna Isabel Ribeiro*, Daniela Dantas, Renata Silva, Fernando Remião, Fátima Cerqueira, Eugénia Pinto, Alice Dias, Andrea Zille16*afr@2c2t.uminho.pt

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Halochromic properties of a 5-aminoimidazole-4-carboxamidrazone and its application to wool

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