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The Lewis base–Lewis acid adducts with the Lewis bases pyrazine, triphenyphosphine, neocuproine (2,9-dimethyl-1,10-phenanthroline), cuproine (2,2′-diquinolyl) and triphenylborane as Lewis acid were prepared. Their electronic spectra are characterized by low-energy electronic transitions which are attributed to phenyl (BPh 3 ) to Lewis base, ligand to ligand charge transfer (LLCT) transitions. These Lewis base-BPh 3 complexes display a distinct blue to green fluorescence in solution which originates from the lowest-energy LLCT singlets. [ABSTRACT FROM AUTHOR]

The complex (phanephos)ReI(CO)3Cl with phanephos=4,12-bis(diphenylphosphino)-[2.2]-paracyclophane is characterized by a lowest-energy intraligand (IL) excited state of the 2,2-paracyclophane moiety. This IL transition appears at λmax=340 nm in absorption and at 383 (fluorescence) and 480 nm (phosphorescence, at r.t.) in emission. [Copyright &y& Elsevier]

The complexes [Re I (L–L)(CO) 3 Cl] with L–L = lumazine and folic acid were prepared and their electronic spectra were measured. The free ligands L–L, as well as both complexes, show an emission which is attributed to the fluorescence of L–L. This luminescence is apparently facilitated by excited state proton transfer. [ABSTRACT FROM AUTHOR]

Abstract: Alizarin complexone (AC) in ethanol shows two fluorescence bands which originate from the lowest excited singlet before and after proton transfer. Upon addition of various metal ions (Ni2+, Zn2+, Gd3+, Th4+) to AC in ethanol the formation of well known AC complexes takes place. They are characterized by intense colours which are caused by IL (or ILCT) transitions. If low-energy LF states (Ni2+) are absent (Zn2+, Gd3+, Th4+) these complexes show a weak fluorescence. Even in the case of Gd and Th a heavy-atom effect is not apparent and fluorescence quenching is not observed. Moreover, AC complexes are not phosphorescent under any conditions. [Copyright &y& Elsevier]

Abstract: Dry silver sulfadiazine (AgSD) is not light sensitive but shows a greenish-blue r.t. photoluminescence at λ max =482nm which is suggested to originate from an IL triplet. In the presence of water AgSD undergoes a partial hydrolysis with the formation of free sulfadiazine (HSD) which has been previously shown to be photoreactive. Moreover, irradiation of an aqueous suspension of AgSD leads also to the photoreduction of Ag+ to elemental silver. This photolysis might explain the origin of argyria which can occur when AgSD in contact with human skin is exposed to sun light [Copyright &y& Elsevier]

Abstract: The complex [Ir(azulene)(1,5-cyclocta-diene)]+ shows long-wavelength absorptions which are assigned to spin-allowed (λ max =536nm) and spin-forbidden (675nm) transitions. They are of mixed MLCT (Ir→azulene) and ILCT (azulene) character. At 77K the solid complex displays an emission (λ max =816nm) which originates from the MLCT/ILCT triplet. At r.t. in solution the complex undergoes a photosubstitution of the azulene ligand. It is suggested that in the CT state the azulene ligand looses its coordinating ability. [Copyright &y& Elsevier]

Abstract: The anhydrous CeX3 solids with X=Cl, Br, I show two emission bands which are separated by ca. 2000cm−1 due to spin–orbit coupling. The longer-wavelength maximum appears at λ max =362nm for CeCl3, 390nm for CeBr3 and 514nm for CeI3. It is suggested that this red shift is caused by an increasing interaction of the cerium 5d orbitals with the halide nd orbitals. Accordingly, the emission originates from a metal-centered 4f5d excited state which is mixed with a cerium 4f→halide nd MLCT state. [Copyright &y& Elsevier]

The complex ethylenebis(indenyl)zirconium(IV) binolate with binol=1,1′-binaphthyl-2,2′-diol is characterized by a lowest-energy ππ* binolate IL (intraligand) excited state (absorption λmax=348 nm). The IL triplet undergoes an emission at λmax=490 nm under ambient conditions. [Copyright &y& Elsevier]

The complex CuI(BTA)(hfac) with BTA=bis(trimethylsilyl)acetylene and hfac=1,1,1,5,5,5-hexa-fluoroacetylacetonate shows a longest-wavelength absorption at at λmax=324 nm (ϵ=5400 M−1 cm−1) which is assigned to a spin-allowed CuI→π* (BTA) metal-to-ligand charge transfer (MLCT) transition. The solid complex displays an emission at λmax=601 nm which is assumed to originate from the lowest-energy MLCT triplet. In solution MLCT excitation leads to the release of the acetylene with 6×10−4 at λirr=333 nm. [Copyright &y& Elsevier]

With regard to its electronic structure, the cation Icoll2+ (coll = collidine or 2,4,6-trimethylpyridine) is viewed as a coordination compound of iodine(I) with a p4 electron configuration. The lowest-energy excited state of Icoll2+ is suggested to be a ππ* collidine intraligand (IL) triplet which appears in absorption (λmax=332 nm, ϵ=250) and emission (λmax=405 nm, φ=0.001, τ∼90 ns). Owing to the heavy-atom effect of iodine this phosphorescence occurs at r.t. The longest-wavelength pp absorption is apparently obscured by the intense spin-allowed IL band at λmax=268 nm. [Copyright &y& Elsevier]

The reaction of tetracycline with K2PtCl4 in glacial acetic acid leads to the dehydration of tetracycline to anhydrotetracycline (ahtc) which coordinates as a bidentate ligand to the PtCl2 moiety. The composition of Pt(ahtc)Cl2 is confirmed by elemental analysis and mass spectrometry. On the basis of the electronic spectra it is suggested that the coordination takes place at the A ring of ahtc while the BCD ring system is preserved as separate chromophore. It is characterized by a long-wavelength absorption and fluorescence which appear at λmax=428 and 550 nm, respectively, for the free ahtc ligand and λmax=425 and 550 nm for Pt(ahtc)Cl2. [Copyright &y& Elsevier]

The complex (dmp)CuI(BH4) with dmp=2,9-dimethyl-1,10-phenanthroline displays a long-wavelength absorption at λmax=465 nm which is assigned to a BH4−→dmp ligand-to-ligand charge transfer (LLCT) transition. In the solid state the LLCT state is emissive (λmax=626 nm). In non-coordinating solvents such as CH2Cl2,CHCl3 or toluene the complex undergoes a photoredox decomposition leading to the generation of metallic copper. At λirr=436 nm (dmp)CuI(BH4) disappears with φ=1.2×10−3. [Copyright &y& Elsevier]

The complex CpCuI(PEt3) with Cp=cyclopentadienyl shows a longest-wavelength absorption at λmax=350 nm (in n-hexane) which is assigned to a Cp−→PEt3 ligand-to-ligand charge transfer (LLCT) transition. An analogy to the ylide Cp−–P+Propyl3 is drawn which displays the Cp− to phosphonium charge transfer (CT) absorption at λmax=267 nm (in n-hexane). Solid CpCu(PEt3) exhibits an emission at λmax=525 nm which is assumed to originate from the LLCT triplet. [Copyright &y& Elsevier]

The salt Ag+SbF6− shows a greenish-yellow luminescence (λmax=528 nm) which originates from a AgI → SbV metal-to-metal charge transfer triplet. [Copyright &y& Elsevier]