Circularly polarized luminescence (CPL) is characterized by the differential emission of right and left circularly polarized light by a chiral molecule. This mini-review describes the recent developments in chiral trivalent europium (Eu­(III)) complexes with effective CPL. CPL has many potential applications in security tags, lasers, and three-dimensional organic electroluminescence devices, which is one of the most intensely investigated topics in molecular luminophores. Eu­(III) complexes have attracted considerable attention as effective CPL luminophores for the above-mentioned applications. In this review, recent studies on the Eu­(III) CPL, including the steric (dimer, tetramer, aggregates, and coordination polymers) and electronic control (mononuclear) of Eu­(III) complexes for the construction of a luminophore with effective CPL, are discussed. The characteristic CPL applications employing the chiral mononuclear Eu­(III) complexes are also described. Chiral Eu­(III) complexes with well-designed organic ligands can result in the establishment of new research areas in the fields of photochemistry and materials science.

The structural and electronic strain of ligands promotes the enhancement of the magnitude of circularly polarized luminescence in chiral Eu(iii) complexes.

This paper reports chiral mixed Eu(iii)–Ln(iii) coordination polymers (Ln = Gd and Sm) for the enhancement of the emission quantum yield (Φtot ≥ 50%), achieved via control of 4f electronic structures.

In this review, we summarize the research progress on π-conjugated Eu(iii) luminophores exhibiting bright emission and their physical sensing applications.

A chiral Eu­(III) coordination polymer with phase-transition behavior, [Eu­(+tfc)3(m-dpeb)] n , (+tfc: (+)-3-trifluoroacetylcamphorato, m-dpeb: 1,3-bis­(diphenylphosphorylethynyl)­benzene) was reported for understanding the effect of polymer chain arrangement (orientation effect) on the circularly polarized luminescence (CPL) in a solid system. The phase-transition behavior of the transformable Eu­(III) coordination polymer was characterized using differential scanning calorimetry and powder X-ray diffraction. The Eu­(III) coordination polymer exhibited phase transition at approximately 180 °C. The magnitude of the CPL intensity was drastically changed because of the phase transition, without coordination geometrical change around the Eu­(III) ion. In this study, the orientation effect of a chiral Eu­(III) coordination polymer on the CPL properties in crystalline solid is demonstrated.

Semiconductor nanomaterials with efficient polarized‐light control in the blue region of the visible spectrum are promising candidates for modern and future photo‐information technology, display devices, and optical sensing applications. New‐type semiconductor Eu(OCN)2 nanocrystals with circularly polarized absorption (CD: circular dichroism) and emission (CPL: circularly polarized luminescence) under an applied magnetic field are demonstrated here for the first time. The effective CD signal at 1.6 T was observed at approximately 440 nm. The dissymmetry factor of CPL under 100 K, gM‐CPL, was estimated to be 0.01. These characteristic circularly polarized absorption and emission phenomena of Eu(OCN)2 nanocrystals should be caused by combination between the “Faraday A and C terms” of the magnetic moment in the excited state. Polarized‐light control using Eu(OCN)2 nanocrystals in the blue‐light region of the electromagnetic spectrum is a large first step into a new world of photo‐functional semiconductor nanomaterials.

Three types of Eu(III) coordination polymers with different distorted chiral ligands, [Eu(+tfc)3(p-dpeb)]n, [Eu(+pfc)3(p-dpeb)]n, and [Eu(+hfc)3(p-dpeb)]n (+tfc: (+)-3-(trifluoroacetyl)camphorate, +pfc: (+)-3-(pentafluoropropionyl)camphorate, +hfc: (+)-3-(heptafluorobutyryl)camphorate, p-dpeb: 1,4-bis(diphenylphosphorylethynyl)benzene) were prepared for elucidating the relationship between...

Efficient long-wavelength visible to NIR-emitting materials have been synthesized by use of rigid planar styrylstilbene as a donor component.