Organostannoxanes have been used as scaffolds for the preparation of multi-chromophore assemblies. A single-step synthesis procedure allows the preparation of compounds in which the number of chromophore units can be varied from two to six. Thus, the reactions of pyrene sulfonic acid (PySO3H) or C16H9CHNC6H3(COOH)2(LH2) with various organotin precursors gave pyrene-containing organostannoxanes, that is, [Ph3 SnPySO3]6 (1), [{(Me2Sn)2(μ3-O)(μ-OH)PySO3}2{(Me2Sn)2(μ3-O)(μ-OH)H2O}2⋅2 PySO3] (2), [{tBu2Sn(OH)PySO3}2] (3), [{(nBuSn)12(O)14(OH)6{PySO3}2] (4), and [{(nBu2Sn)L}3]2⋅C6H5CH3 (5). Compounds 1-5 were characterized by using X-ray crystallography. Compounds 1 and 5 are 24-membered macrocycles. Macrocycle 1 possesses intramolecular π-π stacking interactions. An unusual co-crystal of two tetrameric ladders in 2 was observed in which one of the components of the co-crystal is neutral whereas the other is dicationic and two pyrenesulfonate counterions are present to balance the overall charge. In the solid state these compounds reveal rich supramolecular structures. Photophysical studies on 1-5 reveal that interactions in the solid state lead to considerable broadening of the emission bands.
Synthesis of pyrazolo[1,5-c]quinazolines from four easily available precursors is presented through a one-pot tricyclic Pd(ii)/Ag(i) relay catalysis. The bimetallic relay cascade forges five new chemical bonds by concatenating six discrete chemical steps. The relay catalysis enables four-component assembly of pyrazolo[1,5-c]quinazolines that selectively inhibit EGFR, exhibit apoptosis through the ROS-induced mitochondrial-mediated pathway, and arrest the cell cycle at the G1 phase.
We herein report a novel square-planar complex [Co II L], which was synthesized using the electronically interesting phenalenyl-derived ligand LH 2 = 9,9′-(ethane-1,2-diylbis-(azanediyl))bis(1H-phenalen-1-one). The molecular structure of the complex is confirmed with the help of the single-crystal X-ray diffraction technique. [Co II L] is a mononuclear complex where the Co(II) ion is present in the square-planar geometry coordinated by the chelating bis-phenalenone ligand. The solid-state packing of [Co II L] complex in a crystal structure has been explained with the help of supramolecular studies, which revealed that the π•••π stacking present in the [Co II L] complex is analogous to the one present in tetrathiafulvalene/tetracyanoquinodimethane charge transfer salt, well-known materials for their unique charge carrier interfaces. The [Co II L] complex was employed as the active material to fabricate a resistive switching memory device, indium tin oxide/Co II L/Al, and characterized using the write-read-erase-read cycle. The device has interestingly shown a stable and reproducible switching between two different resistance states for more than 2000 s. Observed bistable resistive states of the device have been explained by corroborating the electrochemical characterizations and density functional theory studies, where the role of the Co II metal center and π-conjugated phenalenyl backbone in the redox-resistive switching mechanism is proposed.
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