Due to the sensitivity for interchanging color by exposure to UV light, designing of fuorescent textiles is highly demanded to be employed in camping, military and sensing purposes. Aromatic compounds containing tetrahydroisoquinoline are known with their biological and medicinal activity, but they are not applied as fuorescent materials. Therefore, the present study focuses on synthesis of tetrahydrothienoisoquinoline derivatives and their application in textile technology to obtain fuorescent cotton fabrics. Four tetrahydrothienoisoquinoline derivatives were synthesized in three steps, starting from 2,4-diacetyl-5-hydroxy-5-methyl-3-(4-methoxyphenyl)cyclohexanone. The chemical structures ofthe synthesized tetrahydrothienoisoquinoline derivatives (Ar1-Ph, Ar2-Ph-Cl, Ar3-Ph-CH3 and Ar4-PhOCH3) were confrmed by infrared spectra, 1 HNMR and 13CNMR. The yields and melting points were both measured for all the synthesized compounds. The tetrahydrothienoisoquinoline derivatives were applied onto the cotton fabrics to obtain Ar1-Ph@ cotton, Ar2-Ph-Cl@cotton, Ar3-Ph-CH3@cotton and Ar4-Ph-OCH3@cotton fabrics. All modifed cotton fabrics were exhibited by green emission under UV lamp (325  nm). The excited modifed cotton fabrics showed an intense fuorescence emission peak at 444–467  nm, related to the implemented compounds. The intensity of the fuorescence peak followed the order of Ar1-Ph@cotton>Ar3-Ph-CH3@ cotton≥ Ar4-Ph-OCH3@cotton>> Ar2-Ph-Cl@cotton. The estimated quantum yield (QY) were 68.79%, 23.15%, 13.83% and 13.38%, for Ar1-Ph, Ar2-Ph-Cl, Ar3-Ph-CH3 and Ar4-Ph-OCH3, respectively. Due to the water insoluble character of tetrahydrothienoisoquinoline derivatives, the modifed fabrics showed quite good durability, as the the quantum yields were marginally diminished by only 10.1 – 12.3%, after 5 washings. The prepared tetrahydrothienoisoquinoline derivatives succeeded for obtaining durable fuorescent textiles, and could be further applied in advanced purposes including technical textiles, sensors/biosensors, smart labeling and anti-counterfeiting purposes.

The starting compounds 7-acetyl-8-aryl-4-cyano1,6-dimethyl-6-hydroxy-5,6,7,8-tetrahydroisoquinoline(2H)-3-thiones 3a,b were synthesized and reacted with some N-aryl-2- chloroacetamides 4a−e in the presence of sodium acetate to produce 7-acetyl-8-aryl-3-(N-arylcarbamoylmethylsulfanyl)-4- cyano-1,6-dimethyl-6-hydroxy-5,6,7,8-tetrahydroisoquinolines 5a− g. Upon heating in ethanol containing sodium ethoxide, they underwent intramolecular Thorpe−Zeigler cyclization, affording the corresponding 7-acetyl-1-amino-6-aryl-2-(N-arylcarbamoyl)- 5,8-dimethyl-8-hydroxy-6,7,8,9-tetrahydrothieno[2,3-c]- isoquinolines 6a−g. Compounds 6c,g,f were converted into the corresponding 1−(1-pyrrolyl) derivatives 7a−c by heating with 2,5-dimethoxytetrahydrofuran in glacial acetic acid. Structures of all synthesized compounds were characterized by elemental and spectral analyses. Also, the crystal structure of compounds 5a was determined by X-ray diffraction analysis.

7-Acetyl-8-aryl-4-cyano-1,6-dimethyl-6-hydroxy-5,6,7,8-tetrahydroisoquinolin3(2H)-thiones 2a,b are prepared and dehydrated to give 7-acetyl-8-aryl-4-cyano-1,6-dimethyl-6- hydroxy-7,8-dihydrodroisoquinolin-3(2H)-thiones 6a,b via a novel method by heating with acetyl chloride in acetic acid. The reaction of both compounds 2a,b and 6a,b with N-aryl-2- chloroacetamides 7a−c under two different conditions gave the same corresponding products, 7- acetyl-8-aryl-3-(N-aryl)carbamoylmethylsulfanyl-4-cyano-1,6-dimethyl-7,8-dihydroisoquinolines 8a−e, in high yields. On treatment of compounds 8a,b,e in methanol with a slightly excess molar amount of sodium methoxide, they underwent intramolecular Thorpe−Ziegler cyclization followed by spontaneous aromatization, providing the planar 7-acetyl-1-amino-6-aryl-2-(Naryl)carbamoyl-5,8-dimethyl-8,9-dihydrothieno[2,3-c] isoquinolines 9a,b,e in good yield. Cyclocondensation reactions of 6a,b with phenyl hydrazine, thiosemicarbazide, or hydrazine hydrate led to the formation of nonplanar (3aR, 4S, 9aS)-pyrazolo[3,4-g]isoquinolines 11a, 11b, and 13, respectively. The reaction of compound 13 with 2-chloromethylquinazolin-4(3H)-one in the presence of anhydrous sodium acetate gave the expected thienopyrazoloisoquinolone 14. Heating the latter compound (14) with triethyl orthoformate in glacial acetic acid afforded the fused heptacyclic compound 15. All of the synthesized compounds were characterized based on their full spectral analyses such as IR, 1 H nuclear magnetic resonance (NMR), and mass spectrometry (MS). Moreover, the crystal structure of compound 6a was elucidated by X-ray diffraction analysis