结构化学最新文献

Organic ligands play a pivotal role in lanthanide luminescence by acting as sensitizers for energy absorption and transfer, a phenomenon known as the fluorescence antenna effect. Herein, we introduce two tetradentate nitrogen ligands renowned for their efficient sensitization of lanthanide luminescence, with their luminous efficacy finely adjustable through subtle modifications to their structure. Through the synthesis of four Eu(III)/Tb(III) mononuclear complexes via the complexation of ligands 6,6′-bis(4,5-dihydrooxazol-2-yl)-2,2′-bipyridine (bpybox, L¹) and 6,6′-bis(4,5-dihydrothiazol-2-yl)-2,2′-bipyridine (thio-bpybox, L²) with europium/terbium trifluorosulfonate, structural analysis reveals that the lanthanide ion coordinates with eight nitrogen atoms from two ligands and one oxygen atom from trifluorosulfonate. Among them, two Eu(III) complexes ([Eu(L¹)₂(SO₃CF₃)](SO₃CF₃)₂ EuL¹ and [Eu(L²)₂(SO₃CF₃)](SO₃CF₃)₂ EuL²) and one Tb(III) complex ([Tb(L¹)₂(SO₃CF₃)](SO₃CF₃)₂ TbL¹) exhibit luminosity, displaying characteristic lanthanide metal ion luminescence characterized by high fluorescence quantum yields and prolonged excited state lifetimes. In contrast, TbL² ([Tb(L²)₂(SO₃CF₃)](SO₃CF₃)₂) is non-luminous, with the sole structural distinction being the substitution of oxygen atoms with sulfur atoms within the ligand. This minor alteration significantly impacts the triplet (³T) state energy level of the ligands, thereby influencing their sensitizing effect on Tb(III) luminescence. These findings underscore the remarkable efficiency of bpybox-type ligands as sensitizers for Ln(III) luminescence, with their structural versatility enabling effective modulation of luminous capacities and efficiency.

Fascinating physico-chemical features of functionalized metallic nanoparticles (MNPs), which offer a high surface-to-volume ratio, biocompatibility, and flexible functionalities, are considered as potential building blocks in functionalized nano/biointerface, facilitating stable biosensing detection response towards various biological analytes. MNPs-based colorimetric biosensors have received enormous attention in chemistry, biology, and medicine owing to their simplicity, practicality, low-cost, high stability, and selectivity. Principally, the colorimetric biosensing is low-cost; it does not require advanced analytical instruments because the change in color of nanoparticle dispersion can be directly read out via the naked-eye, which is indeed used for on-field analysis and point-of-care (POC) analyses. Notably, MNPs such as gold, silver, iron oxide, and cerium oxide have been used for the simple and facile colorimetric detection of biologically important analytes via changes in various colors. In this review, the biosensing mechanism is based on the change in colors of MNPs toward the detection of clinically important biomolecules (glucose, ochratoxin A (OTA), etc.), deoxyribonucleic acid (DNA), prostate-specific antigen (PSA), α-fetoprotein (AFP), lipopolysaccharide (LPS), carcinoembryonic antigen (CEA), and proteins in various real samples. This promising discipline, at the interface of nanomaterials and biosciences, offers extensive projections for interdisciplinary researchers that comprise nanomaterial preparation, bio-element functionalization, and targeted detection in clinical diagnostics. The potential approaches for new colorimetric substrate design, important biosensing characteristics, challenges, and future opportunities for colorimetric biosensing strategies are also described.

Modulation of zeolite porosity, including the size and type of channel and cage, is essential for catalysis and separation. Although zeolites with a variety of porous systems have been synthesized by hydrothermal or post-synthetic routes, there is still a lack of rational control of zeolite porosity in the range of large to medium pore/cage. Herein, based on the rational structure building, the structure similarity between IWV topology with large-pore opening and supercage and NES topology with medium-pore opening and medium cage is discovered. Based on the guidance of structure building, two IWV-derived daughter zeolites with different framework compositions, (Si,Ge)-ECNU-31 and (Si,Ge,Al)-ECNU-31, are hydrothermally prepared with built-in structural weakness due to the presence of a large amount of framework Ge atoms, which are utilized to prepare ECNU-32 zeolite with NES topology through subsequent post-synthetic treatment under controlled condition. It is demonstrated that the parent IWV zeolite with only Ge and Si as framework atoms is benefit in post-treatment to obtain a highly crystalline NES zeolite. In contrast, the co-existence of framework Al atoms in (Si,Ge,Al)-ECNU-31 zeolite enhances its hydrothermal stability in water. However, the treatment with acid and amine solutions causes the partial collapse of zeolite structure. Our results demonstrate that rational selection of the framework composition and post-synthetic parameters are crucial for the transformation of large-pore zeolite to medium-pore zeolite.

To construct efficient room-temperature phosphorescence (RTP) doping systems by simple doping methods, isomers 2-(2-(9H-carbazol-9-yl)benzyl)malononitrile (o-CzCN), 2-(3-(9H-carbazol-9-yl)benzyl)malononitrile (m-CzCN) and 2-(4-(9H-carbazol-9-yl)benzyl)malononitrile (p-CzCN) were designed and synthesized by choosing commercial carbazole. Based on the structure-function relationships of three isomers and excellent compatibility between carbazole and benzocarbazole, 2-(3-(9H-carbazol-9-yl)benzyl)malononitrile (Lm-CzCN) and 2-(3-(5H-benzo[b]carbazol-5-yl)benzyl)malononitrile (m-BCzCN) were prepared by self-made carbazole and 2-naphthylamine. Then, Lm-CzCN/m-BCzCN was constructed and optimized by dissolution and rapid evaporation, as well as tuning the mass ratios between Lm-CzCN and m-BCzCN. Lm-CzCN shows excitation dependent RTP and afterglow lifetimes, as well as concentration dependent RTP emission in poly(vinyl alcohol) (PVA) films, while 1% m-BCzCN@PVA film emits bright green afterglow, with RTP and afterglow lifetimes of 2.303 and 17 s in turn, as well as RTP quantum yield of 0.22. More importantly, Lm-CzCN/m-BCzCN presents ultra-long room temperature phosphorescence, with RTP and afterglow lifetimes of 597.58 ms and 8 s, respectively. Moreover, crystals m-CzCN and p-CzCN, as well as Lm-CzCN/m-BCzCN can be excited by visible light of 440 nm, showing yellow afterglow of 1–4 s. Noteworthy, polymorphism o-CzCN_Y and o-CzCN_B were found, whose different emission was investigated by molecular conformation, intermolecular arrangement and stacking patterns. Finally, multiple encryptions were successfully constructed based on the different luminescent properties.