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The methodical study of trinuclear copper(I) metal complexes phosphorescent vapochromic chemosensor via metal-metal interactions for sensing various volatile organic compounds has piqued the interest of many researchers. Herein, we highlighted the performance of chemosensors trinuclear copper(I) pyrazolate complexes (2Pz1‒2Pz5) with different molecular design short alkyl side chains from the respective pyrazole ligands. The synthesized complexes had demonstrated a high phosphorescent sensing capacity of various alcohol derivatives. Due to weak metal-metal interactions, the complexes give emission bands centered around 553-644 nm at an excitation of 280 nm. We found that the only 2Pz3 chemosensors showed quenching phenomena with a significant decrease in its emission intensity of 100% for exposure in 5 minutes with irreversible performance. Interestingly, we also found that the shifting of the emission center due to the disruption of metal-metal interaction performed by chemosensor 2Pz5 resulting in the best detection performance of methanol and ethanol (∆λ= 60 nm) and propanol (∆λ = 22 nm) showing autonomous recovery within 15 minutes. Based on the findings, the specific balance, such as rigidity and amphiphilicity in the molecular design of chemosensors, is important for the detection of vapors via supramolecular interactions.

Gold(I) pyrazolate complex ([Au 3 Pz3]C 10 TEG) has been widely studied due to its interesting liquid crystalline properties by exhibiting the discotic hexagonal columnar arrangement. Generally, the liquid crystalline properties of the gold complex were confirmed based on their differential scanning calorimetry thermogram and polarized optical microscopy (POM) images. However, there is still no in-depth study on the phase transition in liquid crystals of [Au 3 Pz3]C 10 TEG especially on its structural change at variable temperature. In this study, the resulting liquid crystalline properties of [Au 3 Pz3]C 10 TEG upon being heated and cooled was extensively demonstrated via variable-temperature POM (VT-POM) and small angle X-ray scattering (VT-SAXS). Based on the VT-POM images, it was indicated that [Au 3 Pz3]C 10 TEG displayed a fan-shaped texture for typical arrangements of discotic hexagonal columnar of liquid crystals. Moreover, VT-SAXS results was in good agreement with the VT-POM images as it showed that [Au 3 Pz3]C 10 TEG might consist of two types of stacking system, which are ordered and disordered hexagonal discotic arrangements. Likewise, VT-SAXS analysis also demonstrated that hexagonal columnar mesophase of [Au 3 Pz3]C 10 TEG could be recovered even after the heating and cooling for two cycles.

The scientific investigation based on the molecular design of aromatic compounds for high-performance chemosensor is challenging. This is because their multiplex interactions at the molecular level should be precisely determined before the desired compounds can be successfully used as sensing materials. Herein, we report on the molecular design of chemosensors based on aromatic structures of benzene as the organic motif of benzene-1,3,5-tricarboxamides (BTA), as well as the benzene pyrazole complexes (BPz) side chain, respectively. In the case of BTA, the aromatic benzene acts as the centre to allow the formation of π–π stacking for one-dimensional materials having rod-like arrangements that are stabilized by threefold hydrogen bonding. We found that when nitrate was applied, the rod-like BTA spontaneously formed into a random aggregate due to the deformation of its hydrogen bonding to form inactive nitroso groups for non-optical sensing capability. For the optical chemosensor, the aromatic benzene is decorated as a side-chain of BPz to ensure that cage-shaped molecules make maximum use of their centre providing metal-metal interactions for fluorescence-based sensing materials. In particular, when exposed to benzene, Cu-BPz displayed a blue-shift of its original emission band from 616 to 572 nm (Δ = 44 nm) and emitted bright orange to green emission colours. We also observe a different mode of fluorescence-based sensing materials for Au-BPz, which shows a particular quenching mechanism resulting in 81% loss of its original intensity on benzene exposure to give less red-orange emission (λ = 612 nm). The BTA and BPz synthesized are promising high-performance supramolecular chemosensors based on the non-optical and optical sensing capability of a particular interest analyte.

We report that transparent mesostructured silica/gold nanocomposite materials with an interpore distance of 4.1 nm, as-synthesized from a templated sol–gel synthesis method using discotic trinuclear gold(I) pyrazolate complex, were successfully utilized for the fabrication of thin film mesoporous silica nanocomposites containing gold nanoparticles. The material exhibited a highly ordered hexagonal structure when subjected to a thermal hydrogen reduction treatment at 210 °C. In contrast, when the material was subjected to calcination as a heat treatment from 190 to 450 °C, the thin film nanocomposites showed an intense d100 X-ray diffraction peak. Moreover, gold nanoparticles inside the thin film nanocomposites were confirmed by the presence of the d111 diffraction peak at 2θ = 38.2°, a surface plasmon resonance peak between 500–580 nm, and the spherical shape observed in the transmission electron microscope images, as well as the visual change in color from pink to purple. Interestingly, by simply dipping the material into a reaction solution of 4-nitrophenol at room temperature, the highly ordered structure of the as-fabricated silica/gold nanoparticle thin film composite after thermal hydrogen reduction at 210 °C resulted in an improved catalytic activity for the reduction of 4-nitrophenol to 4-aminophenol compared to the material calcined at 250 °C. Such catalytic activity is due to the presence of gold nanoparticles of smaller size in the silicate channels of the highly ordered mesoporous film nanocomposites.

Column gravity chromatography suffered from several drawbacks such as time-consuming and need a large amount of eluents. Herein we reported an efficient technique for effective separation of amphiphilic trinuclear gold(I) pyrazolate complex ([Au 3 Pz 3 ] C10TEG ) with high polarity based on size-exclusion principle of chromatographic technique. Based on the size-exclusion limit, [Au 3 Pz 3 ] C10TEG having a larger size with molecular weight of 4011.39 Da (4030.40 Da when added Na + ) was successfully eluted and collected firstly from its impurities after being recycled for 2 times. In the chromatogram for first cycle, an intense peak upon excitation at 220 nm for [Au 3 Pz 3 ] C10TEG was observed at retention time of 58 mins, while small peaks due to the presence of impurities was observed in the range between 73 to 85 mins. In the second cycle, the impurities were flushed away before [Au 3 Pz 3 ] C10TEG was successfully collected at retention time of 170 mins in the third cycle. The columns were a set of polystyrene/divinylbenzene (PS/DVB) JAIGEL-1H and -2.5H connected in series having exclusion limit of 1 X 10 3 and 2 X 10 4 in which chloroform was used as the eluent at flow rate of 3.5 mL min -1 . As a result, the visual appearance of dark-yellowish [Au 3 Pz 3 ] C10TEG was successfully purified to give pale-yellowish product. Moreover, differential scanning calorimetry thermogram showed that extra shoulder from impurities at 6.13 °C in the first endothermic peak of [Au 3 Pz 3 ] C10TEG at 0.76 °C was completely removed. Hence, it can be concluded that size-exclusion chromatography can be used as an effective purification method with much more convenience and small consumption of solvents.

We highlight that columnar assembly of self-assembled templates was successfully utilized using sol-gel technique of mesostructured silica for the quality improvement of transparent mesoporous film nanocomposites with a hexagonal structure through appropriate heat treatment methods and self-assembled templates in the removal of organic components. In contrast to the reported mesostructured silica film nanocomposites containing columnar assembly of trinuclear gold(I) pyrazolate complex ([Au3Pz3]C10TEG/silicahex) with calcination at 450 °C, mesostructured silica film nanocomposites from self-assembled template of triphenylene bearing amphiphilic decoxy triethylene glycol side chains (TPC10TEG/silicahex) can be completely collapsed upon calcination at 450 °C. This hexagonal structure can be only preserved with calcination at 250 °C although intensity of its main diffraction peak of d100 at 2θ of 3.70° was significantly decreased. On the other hands, thermal hydrogen reduction at the same temperature was foun...

Gold nanoparticles (AuNPs) having particle size less than 10 nm can exhibit enhancement of surface area to give high activity such as in catalytic reaction. However, it is hard to synthesize AuNPs with small particle size due to the strong agglomeration. Herein we report that channels of mesoporous silica synthesized via the template sol-gel synthesis can be used to prepare AuNPs by calcination method. Mesoporous silica with an interpore distance of 4.1 nm was successfully fabricated as transparent thin film by using an amphiphilic trinuclear gold (I) pyrazolate complex as a template for the sol-gel synthesis. Upon calcination at 450 °C for 3 h, silica film nanocomposites showed red-shifting of surface plasmon resonance (SPR) bands from 518 (AuNPs from the bulk) to 544 nm owing to decreasing of the average particle size. The formation of AuNPs was also supported by the appearance of diffraction peaks of d111 at 2θ = 38.20° having a cubic phase. Moreover, transmission electron microscope (TEM) images and X-ray diffraction (XRD) peaks also showed smaller and more homogenous distribution of AuNPs.

Herein we reported that by introducing a one-dimensional (1D) substrate with a porous structure such as anodic aluminum oxide (AAO) membrane, mesoporous silica/alumina hybrid nanocomposites were successfully fabricated by using amphiphilic triphenylene (TPC10TEG) as a template in sol-gel synthesis (TPC10TEG/silicahex). For the optical study of the nanocomposites, TPC10TEG/silicahex showed absorption peak at 264 nm due to the ordered and long-range π-π stacking of the disc-like aromatic triphenylene core. Moreover, the hexagonal arrangement of TPC10TEG/silicahex was proven based on their diffraction peaks of d 100 and d 200 at 2θ = 2.52° and 5.04° and images of transmission electron microscopy (TEM), respectively. For fabrication of mesoporous silica/alumina hybrid membrane, TPC10TEG/silicahex was drop-casted onto AAO membrane for penetration into the porous structure via gravity. X-ray diffraction (XRD) analysis on the resulted hybrid nanocomposites showed that the diffraction peaks of d 100 and d 200 of TPC10TEG/silicahex were still preserved, indicating that the hexagonal arrangements of mesoporous silica were maintained even on AAO substrate. The morphology study on the hybrid nanocomposites using TEM, scanning electron microscope (SEM) and field emission scanning electron microscope (FE-SEM) showed the successful filling of most AAO channels with the TPC10TEG/silicahex nanocomposites.

Gold nanoparticles (AuNPs) with small particle size have been difficult to be synthesized due to their strong agglomeration. Herein we report that the nanochannels of mesoporous silica synthesized from template sol-gel synthesis were utilized to prepare AuNPs by employing thermal hydrogen reduction. Mesoporous silica composite with an interpore distance of 4.1 nm was successfully fabricated as a thin film by an amphiphilic trinuclear gold(I) pyrazolate complex ([Au3Pz3]C10TEG) as a template. In contrast to calcination method of this composite and the bulk [Au3Pz3]C10TEG complex at 450ºC for 3 h, thermal hydrogen reduction at 250ºC for 2 h showed transmission electron microscope (TEM) images and diffraction pattern with smaller particle size (14.5 nm) and more homogenous distribution of AuNPs with up to 44% of the particle size in the range of 10 to 20 nm. The decreasing of average particle size in this new strategy indicated by the red-shifting of the surface plasmon resonance (SPR) band from 518 (AuNPs from the bulk [Au3Pz3]C10TEG complex) and 544 (calcination) to 558 nm.