Laser-Driven Rapid Synthesis of Metal-Organic Frameworks and Investigation of UV-NIR Optical Absorption, Luminescence, Photocatalytic Degradation, and Gas and Ion Adsorption Properties.

In this study, we designed a platform based on a laser-driven approach for fast, efficient, and controllable MOF synthesis. The laser irradiation method was performed for the first time to synthesize Zn-based MOFs in record production time (approximately one hour) compared to all known MOF production methods with comparable morphology. In addition to well-known structural properties, we revealed that the obtained ZnMOFs have a novel optical response, including photoluminescence behavior in the visible range with nanosecond relaxation time, which is also supported by first-principles calculations. Additionally, photocatalytic degradation of methylene blue with ZnMOF was achieved, degrading the 10 ppm methylene blue (MB) solution 83% during 1 min of irradiation time. The application of laser technology can inspire the development of a novel and competent platform for a fast MOF fabrication process and extend the possible applications of MOFs to miniaturized optoelectronic and photonic devices.

Thioxanthone Dioxide Triplet States Have Low Oxygen Quenching Rate Constants.

With few exceptions, triplet excited states of organic molecules, 3M1, are quenched by ground state molecular oxygen, O2(X3Σg-), with rate constants kq greater than ∼109 M-1 s-1 in fluid solutions. If the energy of the triplet state is above 94 kJ/mol, then such quenching can result in the sensitized production of singlet oxygen, O2(a1Δg). In the interaction between 3M1 and O2(X3Σg-), the magnitudes of both kq and the yield of the O2(a1Δg) depend appreciably on mixing with the M-O2 charge-transfer state. Here, we report that triplet states of several thioxanthen-9-one-10,10-dioxide derivatives have unusually low kq values (as low as ∼1 × 108 M-1 s-1) but have quantum yields for the photosensitized production of O2(a1Δg) that approach unity. Because these molecules possess high oxidation potentials (∼3.5 V vs SCE), we suggest that charge transfer character in the 3M1-O2(X3Σg-) encounter complex is reduced, thereby lowering kq while maintaining high O2(a1Δg) yields. These results provide important experimental support for existing models for the quenching of organic molecule excited states by O2(X3Σg-).

DNA groove binder and significant cytotoxic activity on human colon cancer cells: Potential of a dimeric zinc (II) phthalocyanine derivative.

The interaction of a multi-component system consisting of benzene-1,4-diyldimethanimine-bridged dimeric zinc-phthalocyanine groups (4OMPCZ) with calf thymus DNA (ct-DNA) was investigated using UV-Vis absorption, fluorescence emission spectroscopy methods, and viscosity measurements. The binding constant, Kb, which is an important parameter to gain information about the binding mode, was found as 9.7 × 107 M-1 from the UV-Vis absorption studies. Another important spectrophotometric tool is competitive displacement assays with Ethidium bromide and Hoechst 33342. Through this experiment, a higher KSV value was obtained with Hoechst for the phthalocyanine derivative, 4OMPCZ, and the ct-DNA complex than with ethidium bromide. Additionally, molecular docking studies were conducted to calculate the theoretical binding constant and visualize the interactions of 4OMPCZ with a model DNA. According to docking results, although the interactions are mainly located in the major groove of the DNA helix, due to the wrapping, these interactions can also be extended to the minor groove of the DNA. Spectrophotometric, molecular docking, and viscosity studies revealed that the interaction of 4OMPCZ with DNA is likely to be via the major and minor grooves. The in vitro cytotoxic activity of 4OMPCZ was evaluated by MTT assay on human colon cancer cells (HT29) after 72 h of treatment. 4OMPCZ indicated significant cytotoxic activity when stimulated with UV light compared to the standard chemotherapy drugs, fluorouracil (5-FU), and cisplatin on HT29 colon cancer cells. The IC50 value of 4OMPCZ displayed considerably lower concentrations compared to the standard drugs, 5-FU, and cisplatin.

High sensitivity colorimetric determination of L-cysteine using gold nanoparticles functionalized graphene oxide prepared by photochemical reduction method.

This study aimed for the development of a cost effective and efficient method for L-cysteine detection, without employing expensive instrumentation within a short analysis time. The proposed method has been involved in the photochemical preparation of gold nanoparticles and gold nanoparticles on graphene oxide nanostructures. The gold nanoparticles and gold nanoparticles on graphene oxide acted as simple and sensitive nano-sensors for L-cysteine, due to the molecular structure of the L-cysteine presented -NH2 and -SH, which is very attractive for coordination to gold nanoparticles and crosslink gold nanoparticles causing aggregation and color change. By using the gold nanoparticles on graphene oxide as a probe, the colorimetric detection of L-cysteine in a nanomolar order concentration was demonstrated.

Development of a fluorometric measurement system used in biological samples upon the determination of iron (II) metal ion.

2-thioxanthone thioacetic acid (TXSCH2COOH, T), which has a fluorometric character, was used for new fluorometric system upon Fe(II) analysis in biological samples as the main target. T-BSA binary complex was firstly consisted with non-covalent interactions between T and BSA at the equilibrium concentration as 1.77 × 10-4.M. T-BSA binary complex emission was increased at the ratio of 24.40% due to stabilization property of BSA (pH:7), compared with T emission intensity. Fluorescence emission spectroscopy was used for the all measurements because of an economic, a sensitive and a practical method compared with other spectroscopic analysis. T-BSA-Fe(II) triple complex was also obtained by adding Fe(II) ion to T-BSA binary complex solution. Its characterization was performed to be investigated with optimum excitation wavelength, buffer concentration, pH and temperature as 297 nm, 10-3 M Tris HCl (10-2M NaCI), pH:7.2 at 25 °C, respectively. The results of Fe(II) analysis in serum showed a certain response in fluorometric T-BSA-Fe(II) triple complex measurement system as 50.42 ± 5.8 µg/dL. The analyses of our fluorometric triple complex system were compared with the reference electrochemiluminescence method and similar results were obtained. Fluorometric measurements of T-BSA-Fe(II) triple complex, its characterization and Fe(II) analysis in this system have not been investigated in literature gives originality to our study.

A novel fluorometric measurement system based on triple complex for mercury (II) determination.

T-BSA binary complex was formed with non-covalent interactions between fluorometric 2-thioxanthone thioacetic acid and stabilizator bovine serum albumin by fluorescence emission spectroscopy as a sensible and practical method. T-BSA concentration at 1.77 × 10-4 M was obtained as the most suitable and reliable amount for the formation of T-BSA-Hg(II) triple complex. Trace amount of Hg(II) analyses were achieved by this new fluorometric triple complex system as the primary aim. The emission spectra from 350 nm to 650 nm were assayed on fluorometer for Hg(II) concentrations from 1.77 × 10-8 M to 3.53 × 10-4 M under an excitation wavelength of 337 nm. Hg(II) was found to increase the emission intensity of T-BSA by 50% even at 1.77 × 10-7 M Hg(II). So this new system has strong sensitivity to Hg(II) ion. T-BSA-Hg(II) triple complex formation and its fluorometric characterization have not been investigated in literature yet. This study is critically important to provide Hg(II) analyses in wastewater treatments and biological samples for further studies.

The interaction of light-activatable 2-thioxanthone thioacetic acid with ct-DNA and its cytotoxic activity: Novel theranostic agent.

In this study, a thioxanthone derivative, 2-Thioxanthone Thioacetic Acid (TXSCH2COOH) was used to analyze the type of binding to calf thymus DNA in a physiological buffer (Tris-HCl buffer solution, pH:7.0). Several spectroscopic techniques were employed including UV-Vis absorption and fluorescence emission spectroscopy and viscosity measurements were also used to clarify the binding mode of TXSCH2COOH to ct-DNA. The intrinsic binding constant Kb of TXSCH2COOH-ct-DNA was found as 2.5 × 103 M-1 from the absorption studies. Increasing of fluorescence emission intensity was found approximately 74.4% by adding ct-DNA to the TXSCH2COOH solution. Fluorescence microscopy was employed to display imaging of the TXSCH2COOH-ct-DNA solution. Increasing of the iodide quenching effect was observed when TXSCH2COOH was added to the double stranded DNA and the calculated quenching constants of TXSCH2COOH and TXSCH2COOH-ct-DNA were found to be 1.89 × 103 M-1 and 1.19 × 104 M-1, respectively. Additionally, the iodide quenching experiment was conducted with single stranded DNA which led to a high Ksv value. All the experimental results including the viscosity values of ct-DNA with TXSCH2COOH demonstrated that the binding of TXSCH2COOH to ct-DNA was most likely groove binding. Furthermore, TXSCH2COOH was found to be an A-T rich minor groove binder. This was confirmed by the displacement assays with Hoechst 33258 compared to Ethidium Bromide. The in vitro cytotoxic activity measurements were performed by MTT assay on HT29 cell line for 72 h. TXSCH2COOH exhibited notable cytotoxic activities compared to the standard chemotherapy drugs, fluorouracil (5-FU), cisplatin in tumorigenic HT29 cell line. The 50% growth-inhibitory concentration (IC50) for TXSCH2COOH was 19,8 µg/mL while 5-FU and cisplatin were 28.9 µg/mL, 20 µg/mL, respectively. The increase in cytotoxic effect when TXSCH2COOH is activated by light indicates the potential of being theranostic cancer drug candidate.

Spectrophotometric study on binding of 2-thioxanthone acetic acid with ct-DNA.

Thioxanthone and its derivatives are the most remarkable molecules due to their vast variety of application such as radiation curing that is, until using them as a therapeutic drug. Therefore, in this study it was intended to use 2-Thioxanthone acetic acid with and without NaCl in Tris HCl buffer solution (pH:7.0) to represent the interaction with ct-DNA. The UV-vis absorption spectra of TXCH2COOH in the presence of ct-DNA showed hypochromism and the intrinstic binding constant (Kb) was determined as 6 × 103 L mol-1. The fluoresence intensity of TXCH2COOH with ct-DNA clearly increased up to 101% which indicated that the fluorescence intensity was very sensitive to ct-DNA concentration. The binding constant (K) and the values of number of binding sites (n) and were calculated as 1.8 × 103 L mol-1 and 0.69, respectively. When the quenching constants (Ksv) of free TXCH2COOH and TXCH2COOH, which were bonded with ct-DNA were compared, slightly changed values of Ksv were seen. Moreover, displacement assay with Hoechst 33,258 and viscosity measurements in the presence and absence of NaCl salt also confirmed the binding mode which noted the electrostatic interaction following groove binding between TXCH2COOH and ct-DNA. Last but not least, the salt effect was examined on ct-DNA binding with TXCH2COOH. The results of the experiments indicated that the groove binding was strengthened by NaCl whereas in the high NaCl concentration, the binding ability of TXCH2COOH to ct-DNA was inversely affected.

Studies of the binding mode of TXNHCH2COOH with calf thymus DNA by spectroscopic methods.

In this study, a thioxanthone derivative named 2-(9-oxo-9H-thioxanthen-2ylamino) acetic acid (TX-NHCH2COOH) was used to investigate small molecule and DNA binding interactions. Absorption and fluorescence emission spectroscopy were used and melting studies were used to explain the binding mode of TXNHCH2COOH-DNA. Intrinsic binding constant Kb TXNHCH2COOH was found 6×10(5)M(-1)from UV-Vis absorption spectroscopy. Fluorescence emmision intensity increased by adding ct-DNA to the TXNHCH2COOH and KI quenching experiments resulted with low Ksv value. Additionally, 3.7°C increase for Tm was observed. The observed quenching of EB and ct-DNA complex and increase viscosity values of ct-DNA by addition of TXNHCH2COOH was determined. All those results indicate that TXNHCH2COOH can intercalate into DNA base pairs. Fluorescence microscopy helped to display imaging of the TXNHCH2COOH-DNA solution.

One-component thioxanthone acetic acid derivative photoinitiator for free radical polymerization.

Acetic acid-based thioxanthone (TXCH2 COOH) was synthesized and characterized and used as a photoinitiator for free radical photopolymerization of methyl methacrylate (MMA) in the absence and presence of a tertiary amine (MDEA) in different solvents. Different absorption properties were observed depending on the solvent. Fluorescence and phosphorescence experiments were also carried out successfully. The fluorescence quantum yield was found to be 0.09 and the phosphorescence lifetime was calculated as 138 ms at 77 K. The photoinitiator undergoes efficient intersystem crossing into the triplet state and the lowest triplet state possesses π-π* configuration. Laser flash photolysis experiments show that transient absorption of TXCH2 COOH is similar to the parent thioxanthone and the triplet lifetime was calculated as 2.3 µs at 630 nm.

Thioxanthone hydroquinone-O,O'-diacetic acid: photoinitiator or photostabilizer?

A photoinitiator for free-radical polymerization based on a thioxanthone chromophore containing two acetic acid functions was synthesized and characterized. Photophysical studies such as fluorescence, phosphorescence, and laser flash photolysis in addition to photopolymerization of acrylates were performed to elucidate the radical generation mechanism involving intramolecular electron transfer from the triplet state followed by decarboxylation. We found that the position of the acetic acid substituent is critical for the photoreactivity. In most solvents and acrylic monomers, if the acetic acid functionality is at the 1-position, the singlet excited states are deactivated rapidly before electron transfer can occur, resulting in negligible photoreactivity. The excited-state deactivation probably involves intramolecular H-bonding deactivation. The intramolecular H-bonding is disrupted by solvents that support intermolecular H-bonding, such as DMF and DMSO, leading to efficient intramolecular photoreaction.

N-methyl-N-phenylaminomethyl 2-naphthyl ketone: an X-ray diffraction and density functional theory study.

The crystallographically observed molecular structure of the title compound, C(19)H(17)NO, and its inverted counterpart are compared with that calculated by density functional theory (DFT) at the B3LYP/6-311++G(d,p) level. The results from both methods suggest that the observed molecular conformation of the title compound is primarily determined by intermolecular interactions in the crystal structure. The periodic organization of the molecules is stabilized by weak C-H...O and C-H...pi hydrogen bonds and thus a two-dimensional puckered network consisting of R(4)(4)(22) and R(4)(4)(38) ring motifs is established. The title molecule has a (+)-antiperiplanar conformation about the C-C bond in the aminoacetone bridge. The pyramidal geometry observed around the vertex N atom is flattened by the presence of bulky phenyl and naphthylethanone fragments.