Summary Nitrogen containing compounds such as nitrite ions (NO2−) may cause contaminations to the environment, food and drinking water, and they have a negative effect on human health. In this study, a novel fluorescence sensor was developed by modification of polymeric carbon nitride (CN) with copper(II) acetylacetonate (Cu(acac)2). The polymeric CN was prepared by using urea as a precursor via thermal polymerization technique, while the Cu(acac)2 was introduced onto the polymeric CN via an impregnation method. The formation of polymeric CN can be confirmed from the Fourier transform infrared (FTIR) and the diffuse reflectance ultraviolet visible (DR UV‐Vis) spectroscopies. The polymeric CN exhibited three excitation peaks at 277, 315, and 370 nm owing to the presence of CN, CO, and CN groups, respectively, while there was only one emission peak observed at 455 nm. The emission intensity was decreased with the increase of Cu(acac)2 loading, suggesting certain interactions between the polymeric CN and the added Cu(acac)2. The performances of the polymeric CN and Cu(acac)2/CN composites as fluorescence sensors were evaluated for NO2− detection with concentration range of 0.5‐4 μM. It was revealed that the CN sites in the polymeric CN were the most favored quenching sites for the NO2−. With the addition of Cu(acac)2 (0.1 mol%), the quenching rate for CN sites was enhanced two times higher than that of the polymeric CN. This study demonstrated that the composite is a promising fluorescence sensor for the detection of NO2−.

A new type of naphthoyl-thiourea derivative namely N-(5-methylpyridine)-N 0 -(1-naphthoyl) thiourea (NT) was successfully synthesized prior to form conductive layer in organic light emitting diode (OLED). The structure of compound was determined via single crystal X-ray crystallography analysis and spectroscopically characterized by infrared spectroscopy, 1 H and 13 C nuclear magnetic resonance, UV-Vis, UV-fluorescence, cyclic voltammetry analysis as well evaluated theoretically via Gaussian 09 software employing DFT approach with set of basis function B3LYP/6-31G (d,p). In turn, the compound was deposited onto ITO substrate through electrochemical deposition method prior the electrical conductivity and performance as OLED was investigated via Four Point Probe and Two Point Probe. From the crystal structure, NT crystallizes as triclinic crystal system in P-1 space group, unit cell parameters a = 7.4916(5) Å , b = 9.4050(7) Å , c = 12.0584(9) Å , a = 69.685 (7)°, b = 82.130 (6)°and c = 71.917 (7)°. The conductivity analysis of NT performed better and exhibited semiconductor material; 0.231 Scm -1 under dark condition which indicates this single molecular system can act as potential OLEDs.Graphical Abstract This contribution reports on the design, preparation, and characterization of new type of naphthoyl-thiourea derivative namely N-(5-methylpyridine)-N 0 -(1-naphthoyl) thiourea (NT) prior acting as potential Organic Light Emitting Diode (OLED).

A benzoylthiourea derivative (LTU) and its metal complexation of palladium(II) chloride (MLTU) has been successfully synthesized and characterized via typical spectroscopic and analytical techniques namely IR, 1 H and 13 C Nuclear Magnetic Resonance, UV-Visible and Gas Chromatography Flame Ionization Detector (GC-FID). The Infrared spectrum for LTU shows four significant bands of interest namely ν(N-H), ν(C=O), ν(C-N) and ν(C=S) and the values were observed within the range. The 1 H NMR spectrum for the compound shows expected protons for N-H at δH 10.95 ppm and δH 11.15 ppm while the 13 C NMR spectrum shows resonances of carbonyl (C=O) carbon and thiones (C=S) at δC 168.26 ppm and δC 180.56 ppm, respectively. From UV-Vis spectrum, it shows the presence of n-→ *electronic transitions which are expected to be attributed from the phenyl ring, carbonyl (C=O) and thiones (C=S) chromophores. Complexation of LTU with palladium(II) chloride was done to afford MLTU which in turn, was tested as homogeneous catalyst in Sonogashira cross-coupling reaction. The reaction was monitored by GC-FID at 6 hours reaction period. The percentage conversion of 4bromoacetophenone to the coupled product was 75.73% indicated that MLTU can act as an ideal potential catalyst in the Sonogashira reaction.

Nitrite ion (NO2-) is a toxic inorganic contaminant, which is widely used in industry and agriculture as a food preservative and a fertilizing agent. One of the methods to reduce the toxicity of the NO2- is by oxidizing it into less hazardous compounds, such as nitrate ion (NO3-). In this study, we demonstrated that a simple and green photocatalytic process can be employed to oxidize the NO2- to NO3- over a metal free-carbon nitride photocatalyst under ultraviolet (UV) light irradiation. The carbon nitride was synthesized via pyrolysis of urea precursor by a thermal polymerization process at 823 K for 4 hours. The prepared carbon nitride was then characterized by using X-ray diffractometer (XRD), field emission scanning electron microscope (FESEM), diffuse reflectance UV-visible (DR UV-vis), fluorescence, and Fourier transform infrared (FTIR) spectrophotometers, as well as nitrogen  adsorption-desorption isotherm analyzer. All the characterization results supported the successful synthesis of the carbon nitride. The carbon nitride was then used as the photocatalyst for oxidation of NO2- to NO3- under UV light irradiation for 3 h. The decrease of the NO2- and the formation of the NO3- were analyzed by using a high performance liquid chromatography (HPLC) equipped with Hypersil GoldTM PFP column. The mobile phase used was a mixture of methanol (MeOH) and water (H2O) with the ratio of MeOH:H2O was 30:70. The addition of orthophosphoric acid was required to set the pH at 2.5. The flow rate was fixed at 0.8 ml min-1 and the monitored wavelength was 220 nm. It was revealed that carbon nitride could oxidize NO2- to NO3- with a moderate conversion of 15%. Fluorescence quenching showed that there were good interactions between the emission sites of carbon nitride and the NO2- molecules. The good interactions would be one driving force for the carbon nitride to act as a good photocatalyst to oxidize the NO2- to NO3-. The oxidation pathway by the photogenerated species was also proposed.

Thiourea derivatives have attracted great attention as potential materials to be used in molecular electronics application due to their fairly rigid p-system properties. Thus, in this studyN-((6-metylpyridin-3-yl)carbamothioyl)-1-naphtamide (NT) has been successfully designed, synthesized and characterized by typical spectroscopic techniques namely Infrared Spectroscopy (IR),1H and13C Nuclear Magnetic Resonance (NMR), UV-Vis, Four Point Probe to measure its conductivity and finally ab initio quantum mechanical evaluation at the theoretical level of DFT B3LYP/6-31G (d,p). In turn, NT was coated on the ITO substrate by using electrochemical deposition method. The electrical conductivity of this compound as a thin film exhibited good and ideal result which was 1.7x10-4Scm-1. Owing to this outstanding result, this single molecular system candidate has wide possibilities to be applied in many molecular rectification applications such as Organic Light Emitting diodes (OLED). Further investigation can be carried out by conducting and analyse the I-V curve to measure the efficiency of this compound and other similar molecular frameworks in the near future.