Molecular materials that exhibit stimuli-responsive bistability are promising candidates for the development of molecular switches and sensors. We herein report on the coexistence of a wide thermal hysteretic spin crossover (SCO) effect and a thermally inducible metastable high-spin state at low temperatures achieved with the two new complexes [FeII(Lnpdtz)2(NCX)2] (X = S; Se), with Lnpdtz being (2-naphthyl-5-pyridyl-1,2,4-thiadiazole) and X = S (1) and Se (2). Pronounced π–π-stacking of the aromatic side residues of the ligands enables strong intermolecular interactions, leading to abrupt SCO properties and broad magnetic hysteresis of 10 K for X = S and 58 K for X = Se. In this paper, we also present the pressure-induced spin-state switching around 0.8 GPa. A pronounced thermally induced excited spin state trapping (TIESST effect) is observed for the highly cooperative SCO compounds, which was experimentally followed by low-temperature single crystal structure analysis (20 K) and temperature-dependent Mössbauer spectroscopy.

The design and development of photoinitiating systems applicable to UV or even visible light delivered from light‐emitting diodes (LEDs) has been attracting increasing attention due to their great potential applications in various fields. Compared to the strategy of synthesizing novel compounds, the exploration of existing chemicals with interesting photochemical/photophysical properties for their usage as photoinitiators is more appealing and easily commercialized. Nevertheless, a number of compounds such as monoamino‐substituted anthraquinone derivatives, which are intensively investigated for their photophysical and photochemical properties, have seldom been studied for their roles as photoinitiators under LED irradiation. Herein, three monoamino‐substituted anthraquinone derivatives, that is, 1‐aminoanthraquinone, 1‐(methylamino)anthraquinone and 1‐(benzamido)anthraquinone, are studied for their potential as photoinitiators. The photoinitiation mechanism of these monoamino‐substituted anthraquinone derivatives, when combined with iodonium salt, is first clarified using computational quantum chemistry, fluorescence, steady‐state photolysis, and electron spin resonance spin‐trapping techniques. Then, their photoinitiation ability for the cationic photopolymerization of epoxide and divinyl ether monomers is also investigated.

We report the multistep synthesis of a thiadiazole based ligand (L OMe-Nap ) with a methoxy substituent in the sixposition of the naphthalene ring, along with the corresponding iron(II) [Fe II (L OMe-Nap ) 2 (NCE) 2 ] 1−3 (E = S, Se, and BH 3 ) complexes. We also report the synthesis of the [Fe II (L Nap ) 2 (NCBH 3 ) 2 ] (4) complex with the previously reported L Nap ligand. The complexes obtained were characterized by single crystal X-ray crystallography and SQUID magnetometry in all four cases (1−4). Complex 1 shows a weak thermally induced excited spin state trapping (TIESST) effect up to about 60 K. The effects of the methoxy ligand substituent in altering the noncovalent intramolecular π−π interaction are discussed, as well as the tuning of the switching temperature (T 1/2 ) by the choice of NCE. The S < Se < BH 3 series is established in both families of compounds.

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Three monoamino‐substituted anthraquinone derivatives (AAQs), that is, 1‐aminoanthraquinone (AAQ), 1‐(methylamino)anthraquinone (MAAQ), and 1‐(benzamido)anthraquinone (BAAQ), incorporated with various additives [e.g., triethanolamine (TEAOH) and phenacyl bromide (PhC(═O)CH2Br)] are investigated for their roles as photoinitiating systems of free radical photopolymerization of (meth)acrylate monomers upon the exposure to UV to green LEDs. The AAQs‐based photoinitiating systems, AAQ/TEAOH/PhC(═O)CH2Br and BAAQ/TEAOH/PhC(═O)CH2Br photoinitiators exhibit the highest efficiency for the free radical photopolymerization of DPGDA under the irradiation of blue LED and UV LED, respectively, which is consistent with the extent of overlap between their absorption spectra and the emission spectra of the LEDs. AAQ/TEAOH/PhC(═O)CH2Br photoinitiator can also initiate the free radical photopolymerization of different (meth)acrylate monomers, with an efficiency dependent on the chemical structures of these monomers.

The objective of this experimental work was to study the rheological behavior of blends composed of unsaturated polyester resin and calcium carbonate. The influence of calcium carbonate content on the viscosity of the resin has been first investigated for calcium carbonate contents ranging from 0 to 60 wt%. Furthermore, the influences of shear rate and standing time have also been analyzed for different resin/fillers blends. The experimental results show a complex rheological behavior, and allow us to better control the composite formulation as a function of the required molding characteristics and properties of the final composite.

Due to its favorable optoelectronic properties and the accessibility via Grignard metathesis (GRIM) polymerization, poly(3-hexylthiophene) (P3HT) is one of the most applied conjugated polymers. The 'living' nature of GRIM polymerization enables the modification of the polymer and the installation of desired properties. In the present study, two versatile approaches for the synthesis of anchor group-modified P3HT have been developed, which enable the functionalization of various inorganic nanoparticles. Depending on the polymerization conditions, mono-and bifunctional ethynyl-terminated P3HT or solely monofunctionalized aldehyde-terminated P3HT was synthesized. Afterwards, the quantitative introduction of amine, mono-and multidentate disulfide and catechol anchor groups was performed by copper-catalyzed 1,3-dipolar cycloaddition or via imine formation reactions. The influence of the polymeric ligand structure on the functionalization of nanoparticles was then investigated for CdSe@ZnS quantum dots and TiO 2 nanorods by transmission electron microscopy (TEM) and infrared (IR) spectroscopy. Keywords: click chemistry, conjugated polymers, P3HT, GRIM, hybrid nanocomposites IntroductionThe design of conjugated polymers with favorable optoelectronic properties has been the subject of research for several decades. Early on, the application of these organic semiconductors in organic solar cells, light-emitting diodes, optical waveguides and lasers has been envisioned and tested.1 Besides ring-opening metathesis polymerization (ROMP) and cyclopolymerization, Grignard metathesis (GRIM) polymerization represents one of the few 'living' polymerization techniques capable of synthesizing conjugated polymers.2 First discovered by McCullough et al. 2 in 1993, GRIM polymerization enables the facile synthesis of conjugated polymers such as poly(3-alkylthiophenes) (P3ATs) with a high degree of regioregularity. 3 In addition, the synthesis of block copolymers and the incorporation of well-defined polymer end groups is permitted.4,5 As a result, P3ATs obtained from GRIM polymerization have been established as hole-transporting organic semiconductors and are among the most applied conjugated polymers. 2,6 For the formation of hybrid optoelectronic devices P3ATs have also been combined with their inorganic analogs, e.g. TiO 2 or CdSe, as this approach enables the utilization of outstanding electron-and hole-transporting materials. While the concept of hybrid solar cells or light-emitting diodes appears to be superior to common organic solar cells, a major task is to enable efficient interaction of polymers and inorganic nanoparticles, avoiding microphase-separation typically occurring for polymer/ nanoparticle blends, as this lowers the overall device performance.6 Consequently and from a chemical aspect, functional end groups facilitating an effective interaction of conjugated polymers with inorganic nanoparticles are desirable for hybrid optoelectronic devices. 7,8 This allows a homogeneous dispersion of inorganic and organic ma...