Synthesis of new thiophene derivatives and their use as photostabilizers for rigid poly(vinyl chloride)

Five new thiophenes, namely, N-[(3-bromo-2-methylthiophen-5-yl)methylene]-4-methoxyaniline (4a), N-[(3-bromo-2-methylthiophen-5-yl)methylene]-3,4-dimethoxyaniline (4b), N-[(3-bromo-2-methylthiophen-5-yl)methylene]-3,4-dimethylaniline (4c), 3-[(3-bromo-2-methylthiophen-5-yl)methyleneamino]-2-methylquinazolin-4(3H)-one (4d), and 3-[(3-bromo-2-methylthiophen-5-yl)methyleneamino]-2-isopropylquinazolin-4(3H)-one (4e), have been synthesized. All of these materials brought about a reduction in the level of photodegradation of poly(vinyl chloride) (PVC) films containing the synthesized thiophenes (0.5%; by weight). The results obtained showed that the extent of photostabilization of PVC in the presence of an additive was in the order 4e > 4d > 4b > 4a > 4c. For the most favorable additive (4e), the rate of appearance of infrared absorption bands of degradation products was reduced by around two-thirds, while the quantum yield of chain scission was calculated to be reduced by a factor of more than one thousand. It is suggested that the additives may help stabilize PVC by direct absorption of UV radiation and dissipation of the energy as heat or that electrostatic attraction between the additives and PVC may assist transfer of energy from excited state PVC to the additive, from where it can be dissipated

Synthesis, physical properties, and carbon dioxide uptake of new metal-sulfamethoxazole complexes

Considerable research is currently being undertaken to reduce atmospheric CO2 levels, and a promising approach is capturing and storing the gas using adsorbents. In this regard, the synthesis and investigation of the potential use of new materials as CO2 storage media has attracted attention from both industry and academia. Metal-organic frameworks have a range of unique chemical and physical properties with many applications. Reported here is the synthesis of three new sulfamethoxazole-metal complexes and their use as models for investigation of the influence of the metal on their ability to absorb CO2. A new Schiff base was first synthesized, in 89 % yield, from the condensation of sulfamethoxazole and 4-(dimethylamino)benzaldehyde under acidic conditions. The reaction of the Schiff base with metal (nickel, copper, and cobalt) chlorides in ethanol under reflux gave the corresponding sulfamethoxazole-metal complexes in 71–80 % yield. Several experiments were conducted to assess the uptake of CO2 under different conditions. The complexes have low surface areas (1.36–5.82 m2/g) and average pore volume and diameters of 0.008–0.018 cm3/g and 2.17–4.08 nm, respectively. They showed some ability to adsorb CO2 (323 K and 40 bars), and the storage capacity was 11.2–26.1 cm3/gm. The cobalt-containing complex had the highest CO2 storage capability (26.1 cm3/g) due to its relatively high surface area (5.82 m2/g), pore volume (0.018 cm3/g), pore diameter (4.08 nm), and surface roughness (11.6) compared to the nickel and copper complexes

Synthesis and application of levofloxacin–tin complexes as new photostabilizers for polyvinyl chloride

Polyvinyl chloride (PVC) is a synthetic polymer with a wide range of applications with impact on our daily life. It can undergo photodegradation with toxic products that are hazardous to both human health and the environment. In addition, photodegradation shortens the useful lifetime of the material. Elongation of the effective lifespan of PVC is, therefore, a salient area of research. Recently, a lot of attention has been directed toward the design, preparation, and usage of new additives that are capable of reducing the photodecomposition of PVC. This work investigates the synthesis of new levofloxacin-tin complexes and their potential exploitation against the photodecomposition of PVC. Several levofloxacin-tin complexes have been synthesized, in high yields, by a simple procedure and characterized. The potential use of the additives as photostabilizers for PVC has been investigated through the determination of weight loss, molecular weight depression, formation of fragments containing carbonyl and alkene groups, and surface morphology of irradiated PVC films. The results show that the new additives are effective in reducing the photodegradation of PVC. The new levofloxacin-tin complexes act as absorbers of ultraviolet light and quenchers of highly reactive species such as free radicals produced during photodegradation. They are more effective photostabilizers compared with organotin complexes previously reported. The complexes containing aromatic substituents were more effective than those counterparts having aliphatic residues

Tin complexes of 4-(Benzylideneamino)benzenesulfonamide: synthesis, structure elucidation and their efficiency as PVC photostabilizers

Poly(vinyl chloride) (PVC) suffers from photo-oxidation and photodegradation when exposed to harsh conditions. Application of PVC thus relies on the development of ever more efficient photostabilizers. The current research reports the synthesis of new complexes of tin and their assessment as poly(vinyl chloride) photostabilizers. The three new complexes were obtained in high yields from reaction of 4-(benzylideneamino)benzenesulfonamide and tin chlorides. Their structures were elucidated using different tools. The complexes were mixed with poly(vinyl chloride) at a very low concentration and thin films were made from the blends. The effectiveness of the tin complexes as photostabilizers has been established using a variety of methods. The new tin complexes led to a decrease in weight loss, formation of small residues, molecular weight depression, and surface alteration of poly(vinyl chloride) after irradiation. The additives act by absorption of ultraviolet light, removal the active chlorine produced through a dehydrochlorination process, decomposition of peroxides, and coordination with the polymeric chains. The triphenyltin complex showed the greatest stabilizing effect against PVC photodegradation as a result of its high aromaticity

Crystal structure of (Z)-3-(4-methoxyphenyl)-4-(5-methyl-1-phenyl-1H-1,2,3-triazol-4-yl)-N-phenylthiazol-2(3H)-imine, C25H21N5OS

C25H21N5OS, monoclinic, P21/n (no. 14), a = 12.9303(5) Å, b = 9.1111(4) Å, c = 18.7111(8) Å, β = 97.879(4)°, V = 2183.53(16) Å3, Z = 4, R gt (F) = 0.0487, wR ref (F2) = 0.1327, T = 293(2) K. CCDC no.: 2314057 The molecular structure is shown in the figure. Table 1 contains crystallographic data and Table 2 contains the list of the atoms including atomic coordinates and displacement parameters

Crystal structure of (Z)-3-(3-(4-hydroxyphenyl)-2-(phenylimino)-2,3-dihydrothiazol-4-yl)-2H-chromen-2-one, C24H16N2O3S

C24H16N2O3S, triclinic, P 1 ‾ (no. 2), a = 6.7738(3) Å, b = 11.6072(6) Å, c = 13.6060(9) Å, α = 69.197(6)°, β = 87.025(5)°, γ = 76.990(4)°, V = 973.90(10) Å3, Z = 2, R gt (F) = 0.0482, wR ref (F2) = 1191, T = 293(2) K. CCDC no.: 2314056 The molecular structure is shown in the figure. Table 1 contains crystallographic data and Table 2 contains the list of the atoms including atomic coordinates and displacement parameters

Investigation of the impact of chemical modifications on the photostability of polymethyl methacrylate

For practical application, it is crucial to ensure that polymeric materials are protected against degradation due to aging and ultraviolet (UV) irradiation. A range of advancements in developing novel photostabilizers has been made in the last few years. Another approach is the alteration of polymer structures to enhance their ability to resist photodegradation and photooxidation on exposure to UV light for extended periods in harsh conditions. Polymeric chain modifications have proved to be efficient in increasing the photostability of materials. The current work deals with the surface functionalization of polymethyl methacrylate (PMMA) by incorporating organotin moieties on the polymer backbone. PMMA reacts with ethylenediamine to attach amino groups to the polymer chains. The amino group reacts with 2-hydroxynaphthaldehyde to produce the corresponding Schiff base. Adding trisubstituted (methyl, butyl, and phenyl) tin chloride led to the addition of organometallic residence to the polymeric chains. Thin films of the modified PMMA were made and irradiated with ultraviolet light for long durations to test the effect of chain modification on the photostability of polymeric materials. The effect of the substituent on the tin atom on the photostability of PMMA has been analyzed. Various methods were used for assessment, including infrared spectroscopy, weight loss, surface morphology, and roughness factor. The modified polymers showed increased resistance to photodegradation and had lower roughness factor, weight reduction, surface damages, and small fragments generated compared to the blank PMMA. The polymer containing phenyl substituents showed the most apparent photostabilization effect and the least destructive changes in the PMMA surface on photoirradiation

Pendant modification of poly(methyl methacrylate) to enhance its stability against photoirradiation

Photostabilization of functional polymeric materials is important for protection against aging and ultraviolet (UV) irradiation. There is, therefore, the impetus to modify polymers to increase their resistance to photodegradation and photooxidation on extended exposure to UV light in harsh conditions. Various polymeric additives have been designed and synthesized in recent years, and their potential as photostabilizers has been explored. Reported here is the effect of pendant functionalization of poly(methyl methacrylate) (PMMA) through organometallic moiety incorporation into the polymer’s backbone. The reaction of PMMA with ethylenediamine leads to the formation of an amino residue that can react with salicylaldehyde to produce the corresponding Schiff base. Adding metal chlorides (zinc, copper, nickel, and cobalt) led to the formation of organometallic residues on the polymeric chains. Thin films of modified and unmodified PMMA were produced and irradiated with UV light to determine the effect of pendant modification on photostability. The photostabilization of PMMA was assessed using a range of methods, including infrared spectroscopy, weight loss, decomposition rate constant, and surface morphology. The modified PMMA incorporating organic Schiff base metal complexes showed less photodecomposition than the unmodified polymer or one containing the Schiff base only. Thus, the metals significantly reduced the photodegradation of polymeric materials. The polymer containing the Schiff base-cobalt unit showed the least damage in the PMMA surface due to photoirradiation, followed by those containing nickel, zinc, and copper, in that order

1-(4-Fluorophenyl)-5-methyl-N?-{1-[5-methyl-1-(4-methylphenyl)-1H-1,2,3-triazol-4-yl]ethylidene}-1H-1,2,3-triazole-4-carbohydrazide

The title molecule, C22H21FN8O, comprises fluorophenyl (A), methyltriazolyl (B), methyltriazolyl (C) and tolyl (D) rings. The twist angles between the planes through neighbouring ring pairs A/B, B/C and C/D are 45.0 (1), 9.4 (1) and 43.2 (1)°, respectively. Intermolecular π–π interactions between rings A and C and between B and D propagate the structure in the [010] direction and weak C—H...O interactions also occur

2-[5-(4-Fluorophenyl)-3-(4-methylphenyl)-4,5-dihydro-1H-pyrazol-1-yl]-4-(5-methyl-1-phenyl-1H-1,2,3-triazol-4-yl)thiazole

The title compound, C28H23FN6S, comprises phenyl (A), triazolyl (B), thiazolyl (C), pyrazoyl (D), tolyl (E) and fluorophenyl (F) rings, with twist angles between neighbouring rings pairs A/B, B/C, C/D, D/E and D/F of 64.6 (1), 11.7 (2), 23.5 (2), 8.2 (2) and 73.3 (1)°, respectively. A short intramolecular C—H...N contact and a weak intermolecular C—H...π interaction occur. The crystal chosen for data collection was found to be an inversion twin