Exploring the Orthogonal Chemoselectivity of 2,4,6-Trichloro-1,3,5-Triazine (TCT) as a Trifunctional Linker With Different Nucleophiles: Rules of the Game

Green synthesis of 1,3,5-triazine derivatives using a sonochemical protocol

1,3,5-triazine derivatives are useful compounds with potential applications in various branches of chemical industry, including pharmaceutical chemistry, cosmetic chemistry, photochemistry, and organic chemistry. Due to the growing environmental requirements on conducting efficient, economical, and safe syntheses, development of new methods for synthesizing organic compounds is highly desirable. In this publication, we present a protocol for the synthesis of 1,3,5-triazine derivatives using a sonochemical approach. In as little as 5 min, it is possible to obtain most of the investigated compounds with a yield of over 75%. An undeniable advantage of this method, besides its short time, is the use of water as the solvent. Furthermore, we provide examples that the sonochemical method may be more versatile than the competing microwave method. Analysis conducted using the DOZNTM 2.0 tool revealed that in terms of the 12 principles of green chemistry, the developed sonochemical method is 13 times "greener" than the classical one. Additionally, it has been demonstrated that the investigated molecules are attractive for their application as drug-like compounds.

Sequential nucleophilic aromatic substitutions on cyanuric chloride: synthesis of BODIPY derivatives and mechanistic insights

Herein we report a study on the sequential substitution of different nucleophiles on cyanuric chloride to obtain potential candidates for metal sensors (5a-c). The set of nucleophiles on the 1,3,5-triazine ring includes a phenolic BODIPY, an aminoalkyl pyridine and aminoalkyl phosphoramidates, each one designed to play a specific role in the final fluoroionophore. Three new triazine triads were synthesized in similar yields: 5a (45%), 5b (43%) and 5c (52%) after a methodical sequential combination of the nucleophiles via thermodependent nucleophilic aromatic substitution of the three chlorine atoms of cyanuric chloride. To ratify the synthetic results we simulated the reaction mechanisms for the different nucleophiles, aiming to address the distinctive orthogonality and temperature control inherent in this process, identifying and providing a sound rationale for any preferential sequence of nucleophiles inserted into the triazine core. According to our experimental and computational analysis (thermo- and kinetic preferences), we have identified the following preferential order for the sequential substitution: p-hydroxybenzaldehyde > 2-(pyridin-2-yl)ethanamine > aminoalkyl phosphoramidate, indicating that all steps follow a single-step process (concerted) in two stages, where nucleophilic addition precedes leaving group dissociation. The Meisenheimer σ-complex was identified as a transition state structure, with insufficient stability to exist as an intermediate. We observed a consistent and progressive increase in barrier height: 2-8 kcal mol-1 for the first step, 9-15 kcal mol-1 for the second step, and >15 kcal mol-1 for the third substitution. These findings align with the experimental observation of thermodependency in the sequential substitution.

New triazinephosphonate dopants for Nafion proton exchange membranes (PEM)

A new paradigm for energy is underway demanding decarbonized energy systems. Some of them rely on emerging electrochemical devices, crucial in hydrogen technologies, including fuel cells, CO2 and water electrolysers, whose applications and performances depend on key components such as their separators/ion-exchange membranes. The most studied and already commercialized Nafion membrane shows great chemical stability, but its water content limits its high proton conduction to a limited range of operating temperatures. Here, we report the synthesis of a new series of triazinephosphonate derivatives and their use as dopants in the preparation of new modified Nafion membranes. The triazinephosphonate derivatives were prepared by substitution of chlorine atoms in cyanuric chloride. Diverse conditions were used to obtain the trisubstituted (4-hydroxyphenyl)triazinephosphonate derivatives and the (4-aminophenyl)triazinephosphonate derivatives, but with these amino counterparts, only the disubstituted compounds were obtained. The new modified Nafion membranes were prepared by casting incorporation of the synthesized 1,3,5-triazinephosphonate (TPs) derivatives. The evaluation of the proton conduction properties of the new membranes and relative humidity (RH) conditions and at 60 °C, showed that they present higher proton conductivities than the prepared Nafion membrane and similar or better proton conductivities than commercial Nafion N115, in the same experimental conditions. The Nafion-doped membrane with compound TP2 with a 1.0 wt % loading showed the highest proton conductivity with 84 mS·cm-1.

May 1,3,5-Triazine derivatives be the future of leather tanning? A critical review

Leather is produced by a multi-step process among which the tanning phase is the most relevant, transforming animal skin collagen into a stable, non-putrescible material used to produce a variety of different goods, for the footwear, automotive, garments, and sports industry. Most of the leather produced today is tanned with chromium (III) salts or alternatively with aldehydes or synthetic tannins, generating high environmental concern. Over the years, high exhaustion tanning systems have been developed to reduce the environmental impact of chromium salts, which nevertheless do not avoid the use of metals. Chrome-free alternatives such as aldehydes and phenol based synthetic tannins, are suffering from Reach restrictions due to their toxicity. Thus, the need for environmentally benign and economically sustainable tanning agents is increasingly urgent. In this review, the synthesis, use and tanning mechanism of a new class of tanning agents, 1,3,5-triazines derivatives, have been reported together with organoleptic, physical mechanical characteristics of tanned leather produced. Additionally environmental performance and economic data available for 1,3,5-triazines have been compared with those of a standard basic chromium sulphate tanning process, evidencing the high potentiality for sustainable, metal, aldehyde, and phenol free leather manufacturing.

Asymmetrically Substituted s-Triazine Phosphonates by One-Step Synthesis

Asymmetrically substituted s-triazine phosphonates with up to three different phosphonate groups C3 N3 RR'R" with R, R', R"=PO(OR"') and R"'=for example, methyl, ethyl, isopropyl or n-butyl are interesting as polymer additives like flame retardants. Typically, these compounds are obtained by multiple synthesis steps. However, this leads to high production costs, which are a disadvantage for commercial use. Here we report the one-step synthesis of mixtures of asymmetrical s-triazine phosphonates which is an easy way to adjust the thermal behaviour and other properties such as viscosities of the compounds. The synthesis is based on a Michaelis-Arbuzov reaction. A complete conversion of the reactants to the target compounds is observed which was proofed by detailed 1 H, 13 C and 31 P NMR investigations and elemental analysis. The thermal behaviour was compared with thermogravimetric analysis (TGA).

Design, Synthesis, In Vitro and In Vivo Characterization of CDC42 GTPase Interaction Inhibitors for the Treatment of Cancer

CDC42 GTPases (RHOJ, CDC42, and RHOQ) are overexpressed in multiple tumor types and activate pathways critical for tumor growth, angiogenesis, and metastasis. Recently, we reported the discovery of a novel lead compound, ARN22089, which blocks the interaction of CDC42 GTPases with specific downstream effectors. ARN22089 blocks tumor growth in BRAF mutant mouse melanoma models and patient-derived xenografts (PDXs) in vivo. ARN22089 also inhibits tumor angiogenesis in three-dimensional vascularized microtumor models in vitro. Notably, ARN22089 belongs to a novel class of trisubstituted pyrimidines. Based on these results, we describe an extensive structure-activity relationship of ∼30 compounds centered on ARN22089. We discovered and optimized two novel inhibitors (27, ARN25062, and 28, ARN24928), which are optimal back-up/follow-up leads with favorable drug-like properties and in vivo efficacy in PDX tumors. These findings further demonstrate the potential of this class of CDC42/RHOJ inhibitors for cancer treatment, with lead candidates ready for advanced preclinical studies.

A Theranostic Small-Molecule Prodrug Conjugate for Neuroendocrine Prostate Cancer

After androgen deprivation therapy, a significant number of prostate cancer cases progress with a therapy-resistant neuroendocrine phenotype (NEPC). This represents a challenge for diagnosis and treatment. Based on our previously reported design of theranostic small-molecule prodrug conjugates (T-SMPDCs), herein we report a T-SMPDC tailored for targeted positron emission tomography (PET) imaging and chemotherapy of NEPC. The T-SMPDC is built upon a triazine core (TZ) to present three functionalities: (1) a chelating moiety (DOTA: 1,4,7,10-tetraazacyclododecane-1,4,7,10-tetraacetic acid) for PET imaging when labeled with 68Ga (t1/2 = 68 min) or other relevant radiometals; (2) an octreotide (Octr) that targets the somatostatin receptor 2 (SSTR2), which is overexpressed in the innervated tumor microenvironment (TME); and (3) fingolimod, FTY720-an antagonist of sphingosine kinase 1 that is an intracellular enzyme upregulated in NEPC. Polyethylene glycol (PEG) chains were incorporated via conventional conjugation methods or a click chemistry reaction forming a 1,4-disubstituted 1,2,3-triazole (Trz) linkage for the optimization of in vivo kinetics as necessary. The T-SMPDC, DOTA-PEG3-TZ(PEG4-Octr)-PEG2-Trz-PEG3-Val-Cit-pABOC-FTY720 (PEGn: PEG with n repeating ethyleneoxy units (n = 2, 3, or 4); Val: valine; Cit: citrulline; pABOC: p-amino-benzyloxycarbonyl), showed selective SSTR2 binding and mediated internalization of the molecule in SSTR2 high cells. Release of FTY720 was observed when the T-SMPDC was exposed to cathepsin B, and the released FTY720 exerted cytotoxicity in cells. In vivo PET imaging showed significantly higher accumulation (2.1 ± 0.3 %ID/g; p = 0.02) of [68Ga]Ga-DOTA-PEG3-TZ(PEG4-Octr)-PEG2-Trz-PEG3-Val-Cit-pABOC-FTY720 in SSTR2high prostate cancer xenografts than in the SSTR2low xenografts (1.5 ± 0.4 %ID/g) at 13 min post-injection (p.i.) with a rapid excretion through the kidneys. Taken together, these proof-of-concept results validate the design concept of the T-SMPDC, which may hold a great potential for targeted diagnosis and therapy of NEPC.

Triazine: An Important Building Block of Organic Materials for Solar Cell Application

Since the beginning of the 21st century, triazine-based molecules have been employed to construct different organic materials due to their unique optoelectronic properties. Among their applications, photovoltaics stands out because of the current need to develop efficient, economic, and green alternatives to energy generation based mainly on fossil fuels. Here, we review all the development of triazine-based organic materials for solar cell applications, including organic solar cells, dye-sensitized solar cells, and perovskite solar cells. Firstly, we attempt to illustrate the main synthetic routes to prepare triazine derivatives. Then, we introduce the main aspects associated with solar cells and their performance. Afterward, we discuss different works focused on the preparation, characterization, and evaluation of triazine derivatives in solar cells, distinguishing the type of photovoltaics and the role of the triazine-based material in their performance (e.g., as a donor, acceptor, hole-transporting material, electron-transporting material, among others). Throughout this review, the progress, drawbacks, and main issues of the performance of the mentioned solar cells are exposed and discussed. Finally, some conclusions and perspectives about this research topic are mentioned.

Ultrasound-sensitive cRGD-modified liposomes as a novel drug delivery system

Targeted liposomes enable the delivery of encapsulated chemotherapeutics to tumours by targeting specific receptors overexpressed on the surfaces of cancer cells; this helps in reducing the systemic side effects associated with the cytotoxic agents. Upon reaching the targeted site, these liposomes can be triggered to release their payloads using internal or external triggers. In this study, we investigate the use of low-frequency ultrasound as an external modality to trigger the release of a model drug (calcein) from non-targeted and targeted pegylated liposomes modified with cyclic arginine-glycine-aspartate (cRGD). Liposomes were exposed to sonication at 20-kHz using three different power densities (6.2, 9, and 10 mW/cm²). Our results showed that increasing the power density increased calcein release from the sonicated liposomes. Moreover, cRGD conjugation to the surface of the liposomes rendered cRGD-liposomes more susceptible to ultrasound compared to the non-targeted liposomes. cRGD conjugation was also found to increase cellular uptake of calcein by human colorectal carcinoma (HCT116) cells which were further enhanced following sonicating the cells with low-frequency ultrasound (LFUS).

Foldable Detergents for Membrane Protein Study: Importance of Detergent Core Flexibility in Protein Stabilization

Membrane proteins are of biological and pharmaceutical significance. However, their structural study is extremely challenging mainly due to the fact that only a small number of chemical tools are suitable for stabilizing membrane proteins in solution. Detergents are widely used in membrane protein study, but conventional detergents are generally poor at stabilizing challenging membrane proteins such as G protein-coupled receptors and protein complexes. In the current study, we prepared tandem triazine-based maltosides (TZMs) with two amphiphilic triazine units connected by different diamine linkers, hydrazine (TZM-Hs) and 1,2-ethylenediamine (TZM-Es). These TZMs were consistently superior to a gold standard detergent (DDM) in terms of stabilizing a few membrane proteins. In addition, the TZM-Es containing a long linker showed more general protein stabilization efficacy with multiple membrane proteins than the TZM-Hs containing a short linker. This result indicates that introduction of the flexible1,2-ethylenediamine linker between two rigid triazine rings enables the TZM-Es to fold into favourable conformations in order to promote membrane protein stability. The novel concept of detergent foldability introduced in the current study has potential in rational detergent design and membrane protein applications.

Synthesis of New S-Triazine Bishydrazino and Bishydrazido-Based Polymers and Their Application in Flame-Retardant Polypropylene Composites

In this study six new s-triazine bishydrazino and bishydrazido-based polymers were synthesized via condensation of bishydrazino s-triazine derivatives with terephthaldehyde or via nucleophilic substitution of dichloro-s-triazine derivatives with terephthalic acid hydrazide. The synthesized polymers were characterized by different techniques. The new polymers displayed good thermal behavior with great values in terms of limited oxygen indexed (LOI) 27.50%, 30.12% for polymers 5b,c (bishydrazino-s-triazine based polymers) and 27.23%, 29.86%, 30.85% for polymers 7a–c (bishydrazido-s-triazine based polymers) at 800 °C. Based on the LOI values, these polymers could be classified as flame retardant and self-extinguishing materials. The thermal results also revealed that the type of substituent groups on the triazine core has a considerable impact on their thermal behavior. Accordingly, the prepared polymers were mixed with ammonium polyphosphate (APP) in different proportions to form an intumescent flame-retardant (IFRs) system and were introduced into polypropylene (PP) to improve the flame-retardancy of the composites. The best results were obtained with a mass ratio of APP: 5a–c or 7a–c of 2:1, according to the vertical burning study (UL-94). In addition, the presence of 25% “weight ratio” of IFR in the composite showed great impact and passed UL-94 V-0 and V-1 tests.

Interfering with the Tumor-Immune Interface: Making Way for Triazine-Based Small Molecules as Novel PD-L1 Inhibitors

The inhibition of the PD-1/PD-L1 axis by monoclonal antibodies has achieved remarkable success in treating a growing number of cancers. However, a novel class of small organic molecules, with BMS-202 (1) as the lead, is emerging as direct PD-L1 inhibitors. Herein, we report a series of 2,4,6-tri- and 2,4-disubstituted 1,3,5-triazines, which were synthesized and assayed for their PD-L1 binding by NMR and homogeneous time-resolved fluorescence. Among them, compound 10 demonstrated to strongly bind with the PD-L1 protein and challenged it in a co-culture of PD-L1 expressing cancer cells (PC9 and HCC827 cells) and peripheral blood mononuclear cells enhanced antitumor immune activity of the latter. Compound 10 significantly increased interferon γ release and apoptotic induction of cancer cells, with low cytotoxicity in healthy cells when compared to 1, thus paving the way for subsequent preclinical optimization and medical applications.

Design, Synthesis, and Utility of Defined Molecular Scaffolds

A growing theme in chemistry is the joining of multiple organic molecular building blocks to create functional molecules. Diverse derivatizable structures—here termed “scaffolds” comprised of “hubs”—provide the foundation for systematic covalent organization of a rich variety of building blocks. This review encompasses 30 tri- or tetra-armed molecular hubs (e.g., triazine, lysine, arenes, dyes) that are used directly or in combination to give linear, cyclic, or branched scaffolds. Each scaffold is categorized by graph theory into one of 31 trees to express the molecular connectivity and overall architecture. Rational chemistry with exacting numbers of derivatizable sites is emphasized. The incorporation of water-solubilization motifs, robust or self-immolative linkers, enzymatically cleavable groups and functional appendages affords immense (and often late-stage) diversification of the scaffolds. Altogether, 107 target molecules are reviewed along with 19 syntheses to illustrate the distinctive chemistries for creating and derivatizing scaffolds. The review covers the history of the field up through 2020, briefly touching on statistically derivatized carriers employed in immunology as counterpoints to the rationally assembled and derivatized scaffolds here, although most citations are from the past two decades. The scaffolds are used widely in fields ranging from pure chemistry to artificial photosynthesis and biomedical sciences.

Poly(aryl cyanurate)-Based Thin-Film Composite Nanofiltration Membranes

The successful synthesis of poly(aryl cyanurate) nanofiltration membranes via the interfacial polymerization reaction between cyanuric chloride and 1,1,1-tris(4-hydroxyphenyl)ethane (TPE), atop a polyethersulfone ultrafiltration support, is demonstrated. The use of cyanuric chloride allows for the formation of a polymer that does not contain hydrolysis-susceptible amide bonds that inherently limit the stability of polyamide nanofiltration membranes. In order to achieve a thin defect-free cross-linked film via interfacial polymerization, a sufficient number of each monomer should react. However, the reactivities of the second and third chloride groups of the cyanuric chloride are moderate. Here, this difficulty is overcome by the high functionality and the high reactivity of TPE. The membranes demonstrate a typical nanofiltration behavior, with a molecular weight cutoff of 400 ± 83 g·mol-1 and a permeance of 1.77 ± 0.18 L·m-2 h-1 bar-1. The following retention behavior Na2SO4 (97.1%) > MgSO4 (92.8%) > NaCl (51.3%) > MgCl2 (32.1%) indicates that the membranes have a negative surface charge. The absence of amide bonds in the membranes was expected to result in superior pH stability as compared to polyamide membranes. However, it was found that under extremely acidic conditions (pH = 1), the performance showed a pronounced decline over the course of 2 months. Under extremely alkaline conditions (pH = 13), after 1 month, the performance was lost. After 2 months of exposure to moderate alkaline conditions (pH = 12), the MgSO4 retention decreased by 14% and the permeance increased by 2.5-fold. This degradation was attributed to the hydrolysis of the aryl cyanurate bond that behaves like an ester bond.

The Antiproliferative and Apoptotic Effect of a Novel Synthesized S-Triazine Dipeptide Series, and Toxicity Screening in Zebrafish Embryos

Several derivatives containing morpholine/piperidine, anilines, and dipeptides as pending moieties were prepared using s-triazine as a scaffold. These compounds were evaluated for their anticancer activity against two human breast cancer cell lines (MCF-7 and MDA-MB-231), a colon cancer cell line (HCT-116), and a non-tumorigenic cell line (HEK 293). Tamoxifen was used as a reference. Animal toxicity tests were carried out in zebrafish embryos. Most of these compounds showed a higher activity against breast cancer than colon cancer. Compound 3a-which contains morpholine, aniline, and glycylglycinate methyl ester-showed a high level of cytotoxicity against MCF-7 cells with IC₅₀ values of less than 1 µM. This compound showed a much lower level of toxicity against the non-tumorigenic HEK-293 cell line, and in the in vivo studies using zebrafish embryos. Furthermore, it induced cell cycle arrest at the G2/M phase, and apoptosis in MCF-7 cells. On the basis of our results, 3a emerges as a potential candidate for further development as a therapeutic drug to treat hormone receptor-positive breast cancer.

s-Triazine: A Privileged Structure for Drug Discovery and Bioconjugation

This review provides an overview of the broad applicability of s-triazine. Our many years working with this intriguing moiety allow us to discuss its wide activity spectrum (inhibition against MAO-A and -B, anticancer/antiproliferative and antimicrobial activity, antibacterial activity against MDR clinical isolates, antileishmanial agent, and use as drug nano delivery system). Most of the compounds addressed in our studies and those performed by other groups contain only N-substitution. Exploiting the concept of orthogonal chemoselectivity, first described by our group, we have successfully incorporated different nucleophiles in different orders into s-triazine core for application in peptides/proteins at a temperature compatible with biological systems.

Progress, challenges and future directions of heterocycles as building blocks in iterative methodologies towards sequence-defined oligomers and polymers

Heterocyclic building blocks for iterative methodologies leading to sequence-defined oligomers and polymers are reviewed. Solid- as well as solution-phase methods, challenges surrounding these systems and potential future directions are presented.

Sholkamy E, Ali Khan S, Ul-Haq Z, Sharma A, G. de la Torre B, Albericio F, El-Faham A. Novel 4,6-Disubstituted s-Triazin-2-yl Amino Acid Derivatives as Promising Antifungal Agents

A novel series of 4,6-disubstituted s-triazin-2-yl amino acid derivatives was prepared and characterized. Most of them showed antifungal activity against Candida albicans compared to clotrimazole (standard drug). Compounds bearing aniline derivatives, piperidine and glycine on the triazine core showed the highest inhibition zones at concentrations of 50, 100, 200, and 300 μg per disc. In addition, docking studies revealed that all the compounds accommodated well in the active site residues of N-myristoltransferase (NMT) and exhibited complementarity, which explains the observed antifungal activity. Interestingly, none of these compounds showed antibacterial activity.

Exploiting azido-dichloro-triazine as a linker for regioselective incorporation of peptides through their N, O, S functional groups

In the field of bioconjugation, linker development has witnessed massive growth in recent years. 2,4,6-Trichloro-1,3,5-triazine (TCT) is a tridentate linker that can accommodate three distinct nucleophiles. Herein, the reaction of azido triazine derivatives with nucleophiles (amine, thiol and phenol) is studied. The replacement of first chlorine was performed at 0 °C while that of the last chlorine was achieved successfully at rt. As a proof of concept of this strategy with potential application in biological studies, pentapeptides (Ac-XGGFL-NH₂ where X = Lys or Tyr or Cys) were reacted with 2-azido-4,6-dichlorotriazine to replace the first and second chlorine at 0 °C and at rt, respectively. The reactivity of 2-azido-4,6-dichlorotriazine was found to be similar for the α and ε amine group present in same peptide. These findings demonstrate the applicability of 2-azido-4,6-dichlorotriazine as a linker with potential further application in bioconjugation.

Synthesis and Characterization of New Series of 1,3-5-Triazine Hydrazone Derivatives with Promising Antiproliferative Activity

A new series of s-triazine hydrazone derivatives was prepared based on the reaction of 6-hydrazino-2,4-disubstituted-s-triazine with p-substituted benzaldehyde derivatives using a straightforward synthetic pathway. The antiproliferative activity of all synthesized compounds was evaluated against two human cancer cell lines; breast cancer MCF-7 and colon carcinoma HCT-116 using MTT assay. Among all, 11 compounds have shown strong to moderate antiproliferative activity with IC₅₀ values in the range 1.01–18.20 µM in MCF-7 and 0.97–19.51 µM in HCT-116. The best results were obtained with 4,4’-(6-(2-(pyridin-2-ylmethylene)hydrazinyl)-1,3,5-triazine-2,4-diyl) dimorpholine 11 (IC₅₀ = 1.0 µM and 0.98 µM in MCF-7 and HCT-116 cell lines, respectively). The substituents on the s-triazine core as well as the substituent at the benzylidene moiety have a great effect on the antiproliferative activity. Whereas compounds containing dimorpholino-s-triazine derivatives 8a–e showed more potent antiproliferative in MCF-7 compared to their analogs 7a–f (compounds containing two-piperidine rings), compounds containing one piperidine and one morpholine ring 9a–f showed better IC₅₀ values in the range 10.4–22.2 µM. On the other hand, compounds containing two-piperidine rings 7a–f showed more potent antiproliferative in HCT-116 (IC₅₀ values in the range 8.8–19.5 µM) than their analogs 8a–e and 9a–f.

Synthesis, Characterization of sym-2,4,6-trisubstituted-s-Triazine Derivatives and Their Effects on Flame Retardancy of Polypropylene Composites

Polypropylene (PP) is flammable material, which brings latent danger to the environment and human society. Therefore, developing new environmentally friendly and effective flame-retardant is one of the most important ways to improve the flame retardancy of PP and improve safety during its lifetime. Herein, we describe the synthesis of five sym-2,4,6-trisubstituted-s-triazine derivatives, namely, N2,N4,N6-triphenyl-1,3,5-triazine-2,4,6-triamine (TAT), N2,N4,N6-tris(4-bromophenyl)-1,3,5-triazine-2,4,6-triamine (TBAT), N2,N4,N6-tris(4-chlorophenyl)-1,3,5-triazine-2,4,6-triamine (TCAT), 4,4′,4″-((1,3,5-triazine-2,4,6-triyl) tris(azanediyl)) triphenol (THAT), and N2,N4,N6-tris(4-methoxyphenyl)-1,3,5-triazine-2,4,6-triamine (TMAT), from the reaction of cyanuric chloride and p-substituted aniline employing conventional heating or microwave irradiation. The prepared compounds characterized by different techniques, such as Fourier-transform infrared (FTIR), Ultra-Violet and Visible (UV-Vis), Nuclear Magnetic Resonance spectroscopy (1H-NMR and 13C-NMR), Thermogravimetric Analysis (TGA), and differential scanning calorimetry (DSC). The effect of substituent on the aniline moiety has great impact on its thermal stability, as observed from the TGA and DSC data. Based on the TGA and DSC results, three triazine derivatives TAT, TBAT, and TMAT were used as charring agents in the presence of different proportions of ammonium polyphosphate (APP) to form an intumescent flame-retardant (IFR) system, to improve the flame retardancy of PP. The flammability property of PP was investigated by a vertical burning test (UL94). The results of UL94 revealed that the TXAT/APP (IFR) system influence the PP and could improve the flame retardancy of PP. Best results were obtained with the mass ratio of APP and TXAT 2:1. When the IFR loading was 25 wt%, it displayed great influence and passed V-0 with TMAT, and V-1 with both TAT and TBAT in the UL94 test.

Protocol for synthesis of di- and tri-substituted s-triazine derivatives

The present protocol describes the synthesis of di and tri-substituted s-triazine derivatives•s-Triazine undergoes sequential nucleophilic substitution reaction but order of nucleophile is very crucial.•It is very difficult to substitute any nucleophile except amine once amine is incorporated onto s-triazine.•During the synthesis of O,N-type substituted s-triazine, always O-type should be incorporated first.

Phenol as a Modulator in the Chemical Reactivity of 2,4,6-Trichloro-1,3,5-triazine: Rules of the Game II

2,4,6-Trichloro-1,3,5-triazine (TCT) is a privileged core that has the capacity to undergo sequential nucleophilic substitution reactions. Three nucleophiles, namely phenol, thiol and amine, were studied and the preferential order of incorporation on TCT was found to be first phenol, second thiol and third amine. The introduction of phenol was achieved at −20°C. The incorporation of this nucleophile in TCT helped to replace the third ‘Cl’ at 35°C, which is compatible with a biological context. The atomic charges on ‘Cl’ calculated by theoretical approaches were consistent with the experimental findings.

Di- and tri-substituted s-triazine derivatives: Synthesis, characterization, anticancer activity in human breast-cancer cell lines, and developmental toxicity in zebrafish embryos

Here we report on a small library based on a 4-aminobenzonitile-s-triazine moiety. We used a straightforward orthogonal synthetic pathway to prepare di- and tri-substituted s-triazine derivatives, whose basic structure was modified. The newly synthesized compounds were fully characterized by ¹H NMR, ¹³C NMR and elemental analysis. They showed strong anticancer activity against two human breast cancer cell lines (MIDA-MB-231 and MCF-7), with IC₅₀ values less than 1 µM. These s-triazine compounds were generally more selective towards hormone receptor-positive breast cancer cell line MCF-7 than the triple negative MDA-MB-231 cell line. Zebrafish embryos were used to test the developmental toxicity of the target compounds in vivo. The phenotype of embryos treated with the derivatives resembled that of those treated with estrogen disruptors. This observation strongly supports the notion that that these compounds induce their anticancer activity in human breast cancer cells via targeting the estrogen and progesterone receptors.

Investigating Triorthogonal Chemoselectivity. Effect of Azide Substitution on the Triazine Core

An example of triorthogonal chemoselectivity is reported here for the first time. In this regard, a series of 43 reactions were performed using tridentate s-triazine as a model. In all of the possible cases, the three substitutions were carried out using different nucleophiles at a temperature compatible with biological systems.