LUMINESCENT COMPLEXES OF LANTHANIDE IONS FOR SENSING AND TECNOLOGICAL APPLICATIONS

In the present work, new chiral ligands based on the chiral fragment 1,2- diaminecyclohexane (DACH) and their Ln(III) complexes, soluble in different solvents, have been synthetized and characterized from a structural point of view, in solution and, when possible, in the solid state. Also a deep spectroscopic characterization has been performed. Several experiments have been carried out in order to investigate the optical responsivity in solution towards several anions and therefore the possible applications in the field of (bio)sensing. As far as the applications in the field of OLED (also CP-OLED) are concerned, the spectroscopy of several complexes has been studied in the solid state

A chiral lactate reporter based on total and circularly polarized Tb(iii) luminescence

The coordination features and signaling of a l-lactate ion by a [Tb(bpcd)]+(bpcd = N,N′-bis(2-pyridylmethyl)-trans-1,2-diaminocyclohexane-N,N′-diacetate) complex have been investigated by means of a combination of techniques, including total luminescence, calorimetry and circularly polarized luminescence. The l-lactate/[Tb(bpcd)]+association constant, determined by both luminescence titration and isothermal titration calorimetry, indicates a weak interaction (log K = 1.3-1.45) between the analyte and both enantiomers of the complex. The theoretical DFT calculations suggest that the most likely coordination of l-lactate to the possible stereoisomers of the [Tb(S,S-bpcd)]+complex (trans-O,O or trans-Npy,Npy) is one involving a hydroxyl group. The results of [Tb(rac-bpcd)]+as a chiroptical luminescent probe of l-lactate underline the peculiar role of the chiral 1,2-diaminocyclohexane (DACH) backbone. Indeed, the target anion is capable of inducing CPL activity in the racemic mixture of Tb complexes containing DACH-based ligands. The same is not observed for the achiral analogue [Tb(bped)]+(bped = N,N′-bis(2-pyridylmethyl)ethylenediamine-N,N′-diacetate) complex, likely because of the flexibility of the ethylenic group which allows an interconversion between different isomers which produces a null net CPL activity. Thanks to the differential quantum yield of the two diastereomeric species (R,R)-l and (S,S)-l, one can use the racemic complex to reveal l-lactate by measuring the induced CPL spectrum. Interestingly, this has been demonstrated in a commercial complex solution for medical use, containing several electrolytes, namely Ringer's lactate

The paramagnetic metal effect on the luminescence of rare-earth-metal complexes with pyridine-based nitrogen ligands

The synthesis and the characterization in the solid state are presented of La(III), Gd(III) and Lu(III) nitrate complexes with the pyridine-based ligands L1 (N,N′-bis(2-pyridylmethylidene)-1,2-(R,R+S,S)-cyclohexanediamine) and L2 (N,N′-bis(2-pyridylmethyl)-1,2-(R,R+S,S)-cyclohexanediamine). The crucial role of the nature of both the lanthanide ion and the ligand in the luminescence spectroscopy of the metal complexes, in the solid state at room temperature, is demonstrated and discussed. In particular, the "paramagnetic effect" of the Gd(III) ion inducing an increased phosphorescence emission is observed in the complex with L1 ligand and, in a lesser extent, in the complex with L2 ligand. At variance with this observation, only fluorescence emission of the La(III) and Lu(III) diamagnetic metal complexes is detected. © 2015 Elsevier B.V. All rights reserved

Luminescent Eu3+ complexes in acetonitrile solution: Anion sensing and effect of water on the speciation

In this paper the trifluoromethansulphonate (CF3SO3 12, OTf 12, triflate) Eu3+ complexes of a new family of imine-based ligands with 1:1 ligand to metal mole ratio have been employed for luminescence sensing of NO3 12, F 12, Cl 12, Br 12, I 12, CH3COO 12 and ClO4 12, in non-anhydrous acetonitrile (wet AN = wAN) solution. The ligands show different donor ability and stereochemistry. In particular, they consist of the trans racemic isomers containing pyridine or furan as donating ring [N,N\u2032-bis(2-pyridylmethylidene)-1,2-(R,R+S,S)-cyclohexanediamine, L1; N,N\u2032-bis(2-furanylmethylidene)-1,2-(R,R+S,S)-cyclohexanediamine, L2 and the cis (meso) isomer containing the pyridine ring N,N\u2032-bis(2-pyridylmethylidene)-1,2-(R,S)-cyclohexanediamine, L3]. As far as the sensitivity and the selectivity towards the different anions are concerned, the donor ability of the heteroaromatic ring within the ligand backbone, plays a crucial role: the poorly donating furan-based ligand L2 shows the best sensitivity and selectivity towards nitrate. On the other hand, the stereochemistry of the pyridine-based ligand shows a significant effect on the bromide sensing. The effects of the water content on the stability of these complexes have been also studied. Even though the speciation in non-anhydrous is the same as in anhydrous AN (1:1 EuL and 1:2 EuL2 species), their stability is significantly lower. The reasons for this behavior are proposed to be mainly found in the different solvation of both Eu3+ ion and the ligands. \ua9 201

Phosphorene Is the New Graphene in Biomedical Applications

Nowadays, the research of smart materials is focusing on the allotropics, which have specific characteristics that are useful in several areas, including biomedical applications. In recent years, graphene has revealed interesting antibacterial and physical peculiarities, but it has also shown limitations. Black phosphorus has structural and biochemical properties that make it ideal for biomedical applications: 2D sheets of black phosphorus are called Black Phosphorene (BP), and it could replace graphene in the coming years. BP, similar to other 2D materials, can be used for colorimetric and fluorescent detectors, as well as for biosensing devices. BP also shows high in vivo biodegradability, producing non-toxic agents in the body. This characteristic is promising for pharmacological applications, as well as for scaffold and prosthetic coatings. BP shows low cytotoxicity, thus avoiding the induction of local inflammation or toxicity. As such, BP is a good candidate for different applications in the biomedical sector. Properties such as biocompatibility, biodegradability, and biosafety are essential for use in medicine. In this review, we have exploited all such aspects, also comparing BP with other similar materials, such as the well-known graphene

Circularly Polarized Luminescence from an Eu(III) Complex Based on 2-Thenoyltrifluoroacetyl-acetonate and a Tetradentate Chiral Ligand

A new chiral complex [EuL(tta)2(H2O)]CF3SO3; L = N,N′-bis(2-pyridylmethylidene)-1,2-(R,R + S,S)-cyclohexanediamine; tta = 2-thenoyltrifluoroacetyl-acetonate has been synthesized and characterized from a structural and spectroscopic point of view. The molecular structure in the solid state shows the presence of one chiral L, two tta, and one water molecules bound to the metal center. L and tta molecules can efficiently harvest and transfer to Eu(III) the UV light absorbed in the 250-400 nm range. The forced electric-dipole5D0→7F2emission band dominates the Eu(III) emission spectra recorded in the solid state and in solution of acetonitrile or methanol and the calculated intrinsic quantum yield of the metal ion is around 40-50%. The light emitted by the enantiopure complex shows a sizable degree of polarization with a maximum value of the emission dissymmetry factor (glum) equal to 0.2 in methanol solution. If compared with the complex in the solid state or in acetonitrile solution, then the first coordination sphere of Eu(III) when the complex is dissolved in methanol is characterized by the presence of one CH3OH molecule instead of water. This fact is related to different Eu(III) CPL signatures in the two solvents

Tuning of the sensing properties of luminescent Eu3+complexes towards the nitrate anion

A new family of imine-based ligands containing pyridine or furan as an aromatic donating ring [N,N\u2032-bis(2-pyridylmethylidene)-1,2-(R,R + S,S)-cyclohexanediamine, L1; N,N\u2032-bis(2-furanylmethylidene)-1,2-(R,R + S,S)-cyclohexanediamine, L2 and N,N\u2032-bis(2-thienylmethylidene)-1,2-(R,S)-cyclohexanediamine, L3] has been prepared in high yield by means of an easy synthetic protocol. Their trifluoromethansulphonate (CF3SO3-, OTf-) Eu(iii) complexes have been employed for luminescence sensing of the NO3- anion in an anhydrous acetonitrile solution. Spectrophotometric titrations have been carried out to define the speciation in the solution and study the formation of ternary species occurring with the addition of NO3- anions. The sensing response towards this anion is strongly dependent on the nature of the ligand, the stoichiometry of the complexes and their concentration. \ua9 2016 The Royal Society of Chemistry

The Impact of Optogenetics on Regenerative Medicine

Optogenetics is a novel strategic field that combines light (opto-) and genetics (genetic) into applications able to control the activity of excitable cells and neuronal circuits. Using genetic manipulation, optogenetics may induce the coding of photosensitive ion channels on specific neurons: this non-invasive technology combines several approaches that allow users to achieve improved optical control and higher resolution. This technology can be applied to optical systems already present in the clinical-diagnostic field, and it has also excellent effects on biological investigations and on therapeutic strategies. Recently, several biomedical applications of optogenetics have been investigated, such as applications in ophthalmology, in bone repairing, in heart failure recovery, in post-stroke recovery, in tissue engineering, and regenerative medicine (TERM). Nevertheless, the most promising and developed applications of optogenetics are related to dynamic signal coding in cell physiology and neurological diseases. In this review, we will describe the state of the art and future insights on the impact of optogenetics on regenerative medicine