Effect of surface chemistry on bio-conjugation and bio-recognition abilities of 2D germanene materials

The interest of the scientific community for 2D graphene analogues has been recently focused on 2D-Xene materials from Group 14. Among them, germanene and its derivatives have shown great potential because of their large bandgap and easily tuneable electronic and optical properties. With the latter having been already explored, the use of chemically modified germanenes for optical bio-recognition is yet to be investigated. Herein, we have synthesized two germanene materials with different surface ligands namely hydrogenated germanene (Ge-H) and methylated germanene (Ge-Me) and used them as an optical platform for the label-free biorecognition of Ochratoxin A (OTA), a highly carcinogenic food contaminant. It was discovered that firstly the surface ligands on chemically modified germanenes have strong influence on the intrinsic fluorescence of the material; secondly they also highly affect both the bio-conjugation ability and the bio-recognition efficiency of the material towards the detection of the analyte. An improved calibration sensitivity, together with superior reproducibility and linearity of response, was obtained with a methylated germanene (Ge-Me) material, indicating also the better suitability of the latter for real sample analysis. Such research is highly beneficial for the development and optimization of 2D material based optical platforms for fast and cost-effective bioassays.Ministry of Education (MOE)A.B. gratefully acknowledges Ministry of Education (MOE), AcRF Tier 1 grant (Reference No: RG9/19) for the financial support. J. S. acknowledges the financial support of Grant Agency of the Czech Republic (GACR: 19-17593Y). Z. S. was supported by ERC CZ project LL2003 from the Ministry of Education Youth and Sports (MEYS)

Platinum(II) Complexes of Tridentate ‐Coordinating Ligands Based on Imides, Amides, and Hydrazides: Synthesis and Luminescence Properties

Five Pt(II) complexes are described in which the metal ion is bound to anionic urn:x-wiley:14341948:media:ejic202000879:ejic202000879-math-0003 ‐coordinating ligands. The central, deprotonated N atom is derived from an imide Ar−C(=O)−NH−C(=O)−Ar {PtL1–2Cl; Ar=pyridine or pyrimidine}, an amide py−C(=O)−NH−CH2−py {PtL3Cl}, or a hydrazide py−C(=O)−NH−N=CH−py {PtL4Cl}. The imide complexes PtL1–2Cl show no significant emission in solution but are modestly bright green/yellow phosphors in the solid state. PtL3Cl is weakly phosphorescent. PtL4Cl is formed as a mixture of isomers, bound through either the amido or imino nitrogen, the latter converting to the former upon absorption of light. Remarkably, the imino form displays fluorescence in solution, λ0,0=535 nm, whereas the amido shows phosphorescence, λ0,0=624 nm, τ=440 ns. It is highly unusual for two isomeric compounds to display emission from states of different spin multiplicity. The amido‐bound PtL4Cl can act as a bidentate urn:x-wiley:14341948:media:ejic202000879:ejic202000879-math-0004 ‐coordinating ligand, demonstrated by the formation of bimetallic complexes with iridium(III) or ruthenium(II)

Excited-State Aromatic Interactions in the Aggregation-Induced Emission of Molecular Rotors

Small, apolar aromatic groups, such as phenyl rings, are commonly included in the structures of fluorophores in order to impart hindered intramolecular rotations, leading to desirable solid-state luminescence properties. However, they are not normally considered to take part in through-space interactions that influence the fluorescent output. Here, we report on the photoluminescence properties of a series of phenyl-ring molecular rotors bearing three, five, six, and seven phenyl groups. The fluorescent emissions from two of the rotors are found to originate, not from the localized excited state as one might ex-pect, but from unanticipated through-space aromatic dimer states. We demonstrate that these relaxed dimer states can form as a result of intra- or intermolecular interactions across a range of environments in solution and solid samples, including conditions that promote aggregation-induced emission. Computational modeling also suggests that the formation of aro-matic-dimer excited states may account for the photophysical properties of a previously reported luminogen. These results imply, therefore, that this is a general phenomenon that should be taken into account when designing and interpreting the fluorescent outputs of luminescent probes and optoelectronic devices based on fluorescent molecular rotors