Fabrication of a colorimetric film based on bacterial cellulose/metal coordination framework composite for monitoring food spoilage gas.

A newly designed colorimetric sensing film has been developed to determine the spoilage gas from food deterioration. The fabrication of sensing film used for food labels based on bacterial cellulose and carboxymethyl cellulose composite film (BC/CMC) incorporated with Bis(imidazolium) tetrachlorocuprate, HIm2CuCl4 was focused. The BC/CMC composite films were prepared by vacuum filtration and then dipped into the (5-20 % w/w) HIm2CuCl4 solution. Subsequently, they were dried at 60 °C to obtain the BC/CMC-Cu film. For monitoring fish freshness, the TVB-N level was considered an indicator of determining fish spoilage. In addition, the color change was evaluated and expressed as Lab color values and total color difference (TCD). According to the sensing response, the TCD values of the sensing films had continuously changed, corresponding to the ammonia gas, which is one of the TVB-N gases. Based on the variations in Lab color values exposed to ammonia gas at room temperature, the film color shifted from the initial lime green color to the final blue color due to the substitution of metal-ligand bonding. Finally, this colorimetric sensing film can be employed as a potential food freshness indicator in intelligent packaging.

A Single Crystal Hybrid Ligand Framework of Copper(II) with Stable Intrinsic Blue-Light Luminescence in Aqueous Solution.

Single-crystal solid-liquid dual-phase hybrid organic-inorganic ligand frameworks with reversible sensing response facilitated by external stimuli have received significant attention in recent years. This report presents a significant leap in designing electronic structures that display reversible dual-phase photoluminescence properties from single-crystal hybrid ligand frameworks. Three-dimensional Cu(C3N2H4)4Cl2 complex frameworks were formed through the intermolecular hydrogen bonding and π⋯π stacking supramolecular interactions. The absorption band peaks at 627 nm were assigned to d-d transition showing 10Dq = 15,949 cm-1 and crystal field stabilization energy (CFSE) = 0.6 × 10Dq = 114.4 kJmol-1, while the ligand-to-metal charge transfer (LMCT) of complexes was displayed at 292 nm. The intense luminescence band results from LMCT present at 397 nm. Considering its structure, air stability, framework forming and stable luminescence in aqueous solution, the Cu(C3N2H4)4Cl2 complex shows potential for luminescence Cu-based sensors using emission intensity to detect heavy metal ion species.