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Noninvasive control over the reversible generation of singlet oxygen (1O2) has found the enormous practical implications in the field of biomedical science. However, metal‐free pure organic emitters, connected with a photoswitch, capable of generating "on‐demand" 1O2via triplet harvesting remain exceedingly rare; therefore, the utilization of these organic materials for the reversible control of singlet oxygen production remains at its infancy. Herein, an ambient triplet mediated emission in quinoline‐dithienylethene (DTE)‐core‐substituted naphthalene diimide (cNDI) derivative is unveiled via delayed fluorescence. The quinoline‐DTE‐cNDI triad displayed enhanced photoswitching efficiency via double FRET mechanism. It was found to have direct utilization in controlled photosensitized organic transformations via efficient generation of singlet oxygen (yield ΦΔ~0.55 in DCM and 0.73 in methanol). The designed molecule exhibits a long‐lived emission (τ∼1.1 μs) and very small singlet‐triplet splitting (ΔEST) of 0.13 eV empowering it to display delayed fluorescence. Comprehensive steady state and time‐resolved emission spectroscopy (TRES) analyses along with DFT calculations offer detailed understandings into the excited‐state manifolds of organic compound and energy transfer (ET) pathways involved in 1O2 generation. [ABSTRACT FROM AUTHOR]

A series of boron difluoro bis(diiminate) complexes have been prepared and used to obtain triflate substituted fluoroborane complexes. The corresponding well-defined bis(borenium) cations were subsequently synthesized and structurally authenticated. We are also presenting the first experimental and theoretical study of bis(borenium) cations that are derivative of cationic borinic acid. [ABSTRACT FROM AUTHOR]

Novel isomorphous tetranuclear complexes, [(dppf)Cu(μ3,η2 : 2 : 2‐E2{CpMo(CO)2}2]BF4 [E=P (1), As (4), Sb (5), (dppf=1,1′‐bis‐(diphenylphosphino)‐ferrocene)] and [(dppf)Cu(μ3,η2 : 2 : 2‐PE{CpMo(CO)2}2]BF4 [E=As (2), Sb(3)] were synthesized from the reactions between [(dppf)Cu(MeCN)2][BF4] and tetrahedral molybdenum complexes containing unsubstituted homo‐ and hetero‐diatomic group‐15 elements [(μ,η2 : 2‐E2{CpMo(CO)2}2] [E=P (A), As (D), Sb (E)] and [(μ,η2 : 2‐PE{CpMo(CO)2}2] [E=As (B), Sb (C)], respectively. In all these products, the {Mo2E2} or {Mo2PE} moieties coordinate the Cu(I) center via a rare side‐on η2‐coordination mode. The X‐ray structure analyses of [(dppf)Cu(μ3,η2 : 2 : 1‐PSb{CpMo(CO)2}2][BF4] demonstrate, for the first time, the utilization of an η1‐coordination mode for the ligand complex C to coordinate to the Cu(I) center. All the products were characterized by X‐ray crystallography, NMR and IR spectroscopy, mass spectrometry and elemental analysis. Electrochemical studies also revealed the formation of 1–5, and, further, to understand the structure and bonding of the products, theoretical calculations using density functional theory (DFT) were conducted. [ABSTRACT FROM AUTHOR]

A unique C2 symmetric azine bridged bi-ferrocenyl receptor (4) has been modelled and synthesized. In this work, we are able to synthetically regulate conjugation of the dibenzylidenehydrazine fluorophore unit to unexpectedly reveal metal-coordination driven intramolecular twisting. The present probe shows a dramatic turn-on fluorescence response with 91 fold increment of quantum yield along with 17 nm blue shift upon binding with Hg2+ ions selectively with a limit of detection as low as 15 nM. Upon Hg2+ recognition, the ferrocene/ferrocinium redox peak was anodically shifted by ΔE1/2 = 78 mV, indicating the formation of a new complex species. A plausible binding mode of Hg2+ ions with compound 4 has been proposed based on 1H NMR titration, a high-resolution mass spectrometry (HRMS) study and a density functional theory (DFT) study along with the Job's plot analysis. Interestingly, DFT calculations have revealed that the reason for fluorescence enhancement after coordination to Hg2+ ions is not due to conventional restricted C=N isomerization or interrupted N–N single bond rotation rather it is due to the increase of the π←π* transition at the expense of the n →π* (aromatic) transition of the free ligand. Furthermore, TD-DFT calculations of the first excited singlet state of 4 and [4·Hg2+] revealed the involvement of the aromatic π electrons with the vacant site of Hg2+ ions which may be further attributed to the fluorescence enhancement phenomenon. In addition, receptor 4 was successfully applied for the detection of Hg2+ ions in real samples. [ABSTRACT FROM AUTHOR]

Abstract: The reaction of [(Cp*Mo)2(μ‐Cl)2B2H6] (1) with CO at room temperature led to the formation of the highly fluxional species [{Cp*Mo(CO)2}2{μ‐η2:η2‐B2H4}] (2). Compound 2, to the best of our knowledge, is the first example of a bimetallic diborane(4) conforming to a singly bridged Cs structure. Theoretical studies show that 2 mimics the Cotton dimolybdenum–alkyne complex [{CpMo(CO)2}2C2H2]. In an attempt to replace two hydrogen atoms of diborane(4) in 2 with a 2e [W(CO)4] fragment, [{Cp*Mo(CO)2}2 B2H2W(CO)4] (3) was isolated upon treatment with [W(CO)5⋅thf]. Compound 3 shows the intriguing presence of [B2H2] with a short B−B length of 1.624(4) Å. We isolated the tungsten analogues of 3, [{Cp*W(CO)2}2B2H2W(CO)4] (4) and [{Cp*W(CO)2}2B2H2Mo(CO)4] (5), which provided direct proof of the existence of the tungsten analogue of 2. [ABSTRACT FROM AUTHOR]

A number of heterometallic boride clusters have been synthesized and structurally characterized using various spectroscopic and crystallographic analyses. Thermolysis of [Ru3(CO)12] with [Cp*WH3(B4H8)] (1) yielded [{Cp*W(CO)2}2(μ4-B){Ru(CO)3}2(μ-H)] (2), [{Cp*W(CO)2}2(μ5-B){Ru(CO)3}2{Ru(CO)2}(μ-H)] (3), [{Cp*W(CO)2}(μ5-B){Ru(CO)3}4] (4) and a ditungstaborane cluster [(Cp*W)2B4H8Ru(CO)3] (5) (Cp*=η5-C5Me5). Compound 2 contains 62 cluster valence-electrons, in which the boron atom occupies the semi-interstitial position of a M4-butterfly core, composed of two tungsten and two ruthenium atoms. Compounds 3 and 4 can be described as hetero-metallic boride clusters that contain 74-cluster valence electrons (cve), in which the boron atom is at the basal position of the M5-square pyramidal geometry. Cluster 5 is analogous to known [(Cp*W)2B5H9] where one of the BH vertices has been replaced by isolobal {Ru(CO)3} fragment. Computational studies with density functional theory (DFT) methods at the B3LYP level have been used to analyze the bonding of the synthesized molecules. The optimized geometries and computed 11B NMR chemical shifts satisfactorily corroborate with the experimental data. All the compounds have been characterized by mass spectrometry, IR, 1H, 11B and 13C NMR spectroscopy, and the structural architectures were unequivocally established by crystallographic analyses of clusters 2-5. [ABSTRACT FROM AUTHOR]