Search

A series of four indolo[2,3-e]benzazocines HL1–HL4 and two indolo[2,3-f]benzazonines HL5–and HL6, as well as their respective copper(II) complexes 1–6 were synthesized and characterized by 1H and 13C NMR spectroscopy, ESI...

A series of push−pull chromophores comprising a dimethylamino or diphenylamino electron-donating functionality and a cationic benzothiazolium acceptor with an additional electron-withdrawing group (EWG = NO2 or CN) at various positions of the heterocyclic benzene ring have been synthesized and comprehensively investigated for their linear and quadratic nonlinear optical (NLO) properties by means of UV−visible spectroscopy and hyper-Rayleigh scattering, as well as by quantum-chemical calculations at different levels of theory (B3LYP, CAM-B3LYP, MP2, and RI-CC2). In general, all chromophores under study display large static quadratic hyperpolarizabilities β0, comparable to or in most cases even larger than their conventional stilbazolium-containing analogues, which makes these systems attractive for practical NLO applications. The introduction of an auxiliary EWG into the heterocyclic benzene ring causes a substantial red shift of the intramolecular charge-transfer band. Still, at the same time, this modifi...

Deprotonation of [NiII(H2L1)]I·0.5CH3OH (1), where (H2L1)- represents the ligand pentane-2,4-dione bis(S-methylisothiosemicarbazonate(−), in an ethanol solution of aqueous ammonia under argon affor...

Structural analysis of the solvated mixed-valence (MV) trinuclear iron carboxylate, [Fe3O(HCO2)6(γ-pic)3]·x(γ-pic), 1, (γ-pic = 4-methylpyridine; x ≈ 1.3), has been performed from X-ray diffraction data at four temperatures. Analysis of the X-ray diffraction and variable temperature Mossbauer data for 1 clearly shows the presence of localised valence states for iron atoms at and below 100 K. Both physical methods agree that compound 1 exhibits a continuously growing degree of electron transfer (ET) between the three iron sites with increasing temperature; however, the extent of ET is significantly larger for one of the iron(III) sites. All three terminal γ-pic groups remain ordered at and below room temperature, whereas the γ-pic solvent molecules have a temperature dependent disorder over a number of positions. The distribution of the solvent over disorder positions is suggested to influence the degree of ET between the metal sites. From the molecular geometry in the Fe3O-core, an estimate of 260 cm−1 in energy difference between the two vibronic states corresponding to electronic localisation on either of the two iron atoms involved in ET is obtained. This value is close to an estimate for the energy difference assessed by using a Blume–Emery–Griffith Hamiltonian to describe the localised–delocalised transition in mixed valence molecular compounds.