Aminoisophthalate Bridged Cd(II)-2D Coordination Polymer: Structure Description, Selective Detection of Pd2+ in Aqueous Medium, and Fabrication of Schottky Diode

Highly Sensitive Fluorescent Sensing for Nitrobenzene of CdII Complexes Based on Three Isomers and a Bis-Imidazole Ligand

Detection of nitro pollutants is an important topic in environmental protection. A total of 3 Cd (II) complexes (1-3) based on 3 soft organic isomers, n-(3,5-dicarboxylato benzyloxy) benzoic acid (n = 2, 3 or 4-H3DBB), and a linear N-donor ligand, 3-bis(imidazole-l-ylmethyl) benzene (3-bibz), have been synthesized hydrothermally. Structural diversity of Complexes 1-3 displays the architectural 2D or 3D change: Complex 1 exhibits a 2D network featuring tri-nuclear metal units, Complex 2 is a 3D framework based on similar tri-nuclear metal units, and Complex 3 shows a 3D network with binuclear units. Fluorescent sensing properties exhibited in all these complexes have been discovered to detect nitrobenzene (NB) selectively and sensitively. In particular, Complex 3 possesses high sensitivity for NB with the lowest detection limit of 1.15 × 10-10 M. The results of the theoretical calculation verified the fluorescence detection mechanism of NB by these Cd-based complexes. Therefore, these Cd-based complexes might be used as excellent luminescent sensors for NB.

Fluorescent MOF and Its Gel Composite for the Fluorescence Recovery "Turn-On" Detection of Al3+ Ions and "Turn-Off" Detection of Oxo-Anions

The exploration of smart sensors is of great significance for the selectivity, sensitivity, and ability to show the low detection limit for the target analyte. Here, we have used the linker H2L (5-((anthracen-9-ylmethyl)amino)isophthalic acid) for the construction of {[Cd(L)(DMF)(H2O)2]·H2O}n (1) which is in order with the chromophore anthracene moiety and the free -NH functionality as a guest interaction site. This framework showed the luminescence recovery "turn-on" detection of the Al3+ ion in an aqueous solution. An exhaustive mechanism study disclosed that the Lewis acid-base-type interaction between the Al3+ ion and the -NH functionality of the linker in the framework revealed that the absorbance caused an enhancement for the "turn-on" sensing event. Besides the "turn-on" sensing event, the "turn-off" sensing phenomenon of 1 is also noticed when it detects the hazardous oxo-anions (MnO4- and CrO42-) with limit of detection values of 17.08 and 19.91 ppb, respectively. The detection of these diverse analytes are very fast (10 s) and they can also be recognized through a colorimetric response. The sensing mechanisms for these analytes are established by photoinduced electron transfer, Forster resonance energy transfer, and inert filter effect along with theoretical investigation. Furthermore, to show the sensing application of 1 in a versatile podium, a MOF gel composite, 1@AA (AA = Agar-Agar), was developed from 1 with AA. Interestingly, 1@AA showed the colorimetric detection of these analytes under UV light. Therefore, sensor 1 behaves as a smart sensory material for the recognition of the above analytes through a simultaneous "turn-on" and "turn-off" effect.

Coordination polymers: a promising candidate for photo-responsive electronic device application

The design and synthesis of electrically conductive coordination polymers (CPs) are of special interest due to their applications in the fabrication of many environmentally benign emerging technologies, such as molecular wires, photovoltaic cells, light emitting diodes (LEDs), field effect transistors (FETs) and Schottky barrier diodes (SBDs). Owing to their structural flexibility, easy functionality and adjustable energy levels, CPs are promising candidates for providing a better pathway for superior charge transport. Again, the utilization of visible light as an external stimulus to control and manoeuvre the electrical properties of the CPs is exceptionally motivating for the development of many optoelectronic devices, such as photodetectors, photo-switches, photodiodes and chemiresistive sensors. The applications of such materials in devices will solve questions regarding the energy crisis and environmental concerns. This study provides an overview of the recent advances in the development of photo-responsive CPs and the possibility of their application in developing optoelectronic devices. In this regard, a thorough literature survey was performed and the studies related to the fabrication of photosensitive conducting CPs for applications in optoelectronic devices are listed.