Synthesis and properties of benzothioxanthene dicarboximide hydroperoxide: an efficient ‘time-resolved’ DNA photocleaver with long-wavelength

Investigation of the K4[Fe(CN)6]-Mediated Mono- and Bis-Palladium-Catalyzed Cyanation of the Benzothioxanthene Core

The pallado-catalyzed cyanation of benzothioxanthene imide (BTXI) derivatives is explored herein. Once optimized on the monobromo BTXI, mild reaction conditions were successfully applied to the dibromo derivative affording two regioisomers that have been isolated and structurally solved. Additional hydrogen-deuterium exchange experiments were carried out to support a proposed mechanism involving the formation of a five-membered palladacycle intermediate in the bay area. As well as impacting the structural, photo physical and electrochemical properties of the BTXI core, nitrile moieties were successfully used as orthogonal protecting groups, thus opening doors to new design principles.

Nitration of benzothioxanthene: towards a new class of dyes with versatile photophysical properties

The selective mono-nitration of benzothioxanthene (BTXI) is demonstrated here, opening doors to a wide range of structures and reactions. In addition, a new series of derivaties was characterized expanding the scope for electronic organic purposes.

Sulfhydryl-Directed Iridium-Catalyzed C-H/Diazo Coupling and Tandem Annulation of Naphthalene-1-thiols

The first sulfhydryl-directed iridium-catalyzed C-H/diazo coupling and tandem annulation of naphthalene-1-thiols has been developed. The framework of naphtho[1,8-bc]thiopyrans was constructed in a one-step reaction with good yields. This transformation provides a practical synthetic route for the widely used naphtho[1,8-bc]thiopyran derivatives.

Fluorescence ratiometric pH sensor prepared from covalently immobilized porphyrin and benzothioxanthene

A fluorescence ratiometric sensor for pH determination is described in this paper. The sensor incorporated the pH-sensitive dye meso-5,10,15,20-tetra-(4-allyloxyphenyl)porphyrin (TAPP) as an indicator and a pH-insensitive dye N-(2-methacryloxyethyl)benzo[k,l]thioxanthene-3,4-dicarboximide (MBTD), a benzothioxanthene derivative, as a reference for fluorescence ratiometric measurement. To prevent leakage of the dyes, both were photocopolymerized with acrylamide, hydroxyethyl methacrylate, and triethylene glycol dimethacrylate on the silanized glass surface. The reproducibility and response time of the prepared sensor were sufficient. Most common coexisting inorganic ions and organic compounds did not interfere with pH sensing. In the acidic pH range from 1.5 to 5.0 the fluorescence intensity ratio of the two dyes varied linearly as a function of pH. The sensing membrane was found to have a lifetime of at least one month. The sensor was applied to the analysis of waste water and artificial samples.

Novel heterocyclic family of phenyl naphthothiazole carboxamides derived from naphthalimides: synthesis, antitumor evaluation, and DNA photocleavage

A new heterocyclic family of (2-(dimethylamino)ethyl)-2-substituted phenylnaphtho[2,1-d]thiazole-5-carboxamides modified from naphthalimides was designed, synthesized, and quantitatively evaluated as antitumor agents and photonucleases. All these compounds were found to be more cytotoxic against P388 than against A549. B(3) (m-NO(2)) was found to be the strongest inhibitor for P388 with IC(50) of 1.49 microM, while B(2) was the most cytotoxic compound against A549 with IC(50) of 12 microM. B(4) (p-CH(3)), the most efficient DNA photocleaver, showed detectable DNA cleavage at 0.5 microM and total cleavage from form I to 100% form II at 50 microM. The photocleaving mechanism was changed with the modification to be via superoxide anion and radical.

Novel 2-aminothiazonaphthalimides as visible light activatable photonucleases: effects of intercalation, heterocyclic-fused area and side chains

A new family of 2-aminothiazonaphthalimides with different side chains as novel intercalative and visible light activatable photonucleases, was designed, synthesized and quantitatively evaluated. The order of their photocleaving abilities was parallel to that of their intercalative properties. The compound with linear heterocyclic-fused chromophore could intercalate into and photocleave DNA more efficiently than the one with angular heterocyclic-fused chromophore. B(2), the most efficient compound, caused obvious DNA damage at 1 microM. Mechanism experiment showed that superoxide anion was involved.

Five-member thio-heterocyclic fused naphthalimides with aminoalkyl side chains: intercalation and photocleavage to DNA

Novel five-member thio-heterocyclic fused naphthalimides with aminoalkyl side chains were designed, synthesized and evaluated. These compounds have high Scatchard binding constants. They could damage DNA (supercoiled pBR322) from form I (closed) to II (nicked) at a concentration as low as 10 microM and from form I to form III at a concentration of 50 microM. The results implied that the influence of intercalating ability of chromophores on photocleaving ability of photocleavers depended on the mechanism of photocleavage.

Novel naphthalimide hydroperoxide photonucleases: The role of thiocyclic-Fused area and the difference in spectra, photochemistry and photobiological activity

Novel five- and six-membered thiocyclic-fused naphthalimide hydroperoxides (7, 8) as photonucleases were designed, synthesized via unusual isomerization in Pschorr cyclization and photooxygenation. The five-membered 7 was able to induce single-strand nicks in duplex DNA pH independently (7.0-8.5) at 0.5 microM under 366 nm, while the six-membered 8 could photonick the duplex DNA pH dependently (7.0-8.5) at 5 microM under 450 nm and showed 'time-controlled' photo-bioactivity. Their thiocycles and the angular conjugated plane have contributions to their binding affinity with DNA and photocleaving efficiency.

Thiadiazole: A new family of intercalative photonuclease with electron transfer and radical mechanisms

A new family of photonuclease, thiadiazole-naphthalimide were synthesized and evaluated. Thiadiazole group was incorporated for the first time. These compounds intercalated into DNA efficiently and damaged DNA as low as 10 microM photochemically. Mechanism experiment showed that electron transfer and radicals were involved.