Mesomorphism and Photophysics of Some Metallomesogens Based on Hexasubstituted 2,2':6', 2''-Terpyridines : 6', 2''-Terpyridines

The luminescent and mesomorphic properties of a series of metal complexes based on hexacatenar 2,2':6',2''-terpyridines are investigated using experimental methods and density functional theory (DFT). Two types of ligand are examined, namely 5,5''-di(3,4,5-trialkoxyphenyl)terpyridine with or without a fused cyclopentene ring on each pyridine and their complexes were prepared with the following transition metals: ZnII, CoIII, RhIII, IrIII, EuIII and DyIII. The exact geometry of some of these complexes was determined by single X-ray diffraction. All complexes with long alkyl chains were found to be liquid crystalline, which property was induced on complexation. The liquid-crystalline behaviour of the complexes was studied by polarising optical microscopy and small-angle X-ray diffraction. Some of the transition metal complexes (for example, those with ZnII and IrIII) are luminescent in solution, the solid state and the mesophase; their photophysical properties were studied both experimentally and using DFT methods (M06-2X and B3LYP)

Stereoisomeric Homo- and Hetero-Binuclear Iridium(III) Complexes with 3-Oxidopicolinate Bridging Ligand and Their Application in OLEDs

The small and simple 3-hydroxypyridine-2-carboxylic acid (Hpic-OH) is explored as asymmetric bridging ligand for the synthesis of neutral binuclear cyclometalated iridium(III) complexes. Once fully deprotonated the picO2– ligand can act as ancillary ligand toward two iridium centers adopting both the N^O– and O^O– chelation modes. To tune the energy of the excited states within such binuclear complexes, the 2-(2,4-difluorophenyl)pyridine (Hdfppy) and the 2-phenylbenzothiazole (Hpbtz) are used as cyclometalating ligands to respectively obtain both blue- or orange-emissive homo-cyclometalated complexes (BB and YY, with formula [Ir(dfppy)2]2(picO) and [Ir(pbtz)2]2(picO), respectively). Moreover, for the first time, short-bridged hetero-cyclometalated binuclear complexes are also obtained (BY and YB, with formula [Ir(dfppy)2](picO)[Ir(pbtz)2] and [Ir(pbtz)2](picO)[Ir(dfppy)2]). Depending on the reciprocal arrangement of the cyclometalating ligands on the two sides of the small picolinate bridge, two couples of diastereoisomers are obtained and efficiently separated, as proved by combined NMR and DFT studies. The reported binuclear complexes are highly emissive with photoluminescence quantum yields (PLQYs) up to 67%, which are comparable to those of their mononuclear analogues (B and Y). Due to the full reversibility of their redox processes, all the complexes are also tested in solution-processed organic light-emitting diodes, providing unique OLEDs based on hetero-binuclear cyclometalated iridium(III) complexe

Amending the anisotropy barrier and luminescence behavior of heterometallic trinuclear linear M-II-Ln(III)-M-II (Ln(III)=Gd, Tb, Dy; M-II=Mg/Zn) complexes by change from divalent paramagnetic to diamagnetic metal ions

The sequential reaction of a multisite coordinating compartmental ligand LH4 [2-(2-hydroxy-3-(hydroxymethyl)-5-methylbenzylideneamino)-2-methylpropane-1,3-diol] with appropriate lanthanide salts followed by the addition of Mg(NO3)2·6H2O or Zn(NO3)2·6H2O in a 4:1:2 stoichiometric ratio in the presence of triethylamine affords a series of isostructural heterometallic trinuclear complexes containing [Mg2Ln]3+ [Ln = Dy (1), Gd (2) and Tb (3)] and [Zn2Ln]3+ [Ln = Dy (4), Gd (5) and Tb (6)] cores. The formation of 1-6 is demonstrated by X-ray crystallography as well as ESI-MS spectra. All complexes are isostructural possessing a linear trimetallic core with a central lanthanide ion. In this article we have discussed the comprehensive studies, involving synthesis, structure, magnetism and photophysical properties on this family of trinuclear [Mg2Ln]3+ and [Zn2Ln]3+ heterometallic complexes. Complexes 1 and 4 show slow relaxation of the magnetization below 12 K under zero applied direct-current field, but without reaching a neat maximum which is due to the overlapping with a faster quantum tunnelling relaxation mediated through dipole-dipole and hyperfine interactions. Under a small applied direct-current field of 1000 Oe the quantum tunneling was almost suppressed and temperature and frequency dependent peaks were observed, thus confirming the SMM behavior of complexes 1 and 4. The fit of the high-temperature relaxation times to the Arrhenius equation affords an effective energy barrier for the reversal of the magnetization of Ueff =72(2) K with o = 8 x 10-9 s for the SR process and Ueff = 61(2) K with o = 4 x 10-7 s for the FR process for 1 whereas for 4, an effective energy barrier for the reversal of the magnetization Ueff = 67(3) K with o = 4.5 x 10-8 s. To rule out the involvement of intermolecular collaborative interactions in the dynamic of relaxation, we have performed ac susceptibility measurements on 1:10 Dy:Y magnetic diluted samples of of 1 and 4, named as 1' and 4'. Interestingly, the diluted compounds 1' and 4' exhibits SMM behavior under zero magnetic field, thus suggesting that their relaxation processes are single molecular in origin and arise from the M-Dy-M unit. Ab initio CASSCF+RASSI calculations carried out on 1 and 4 confirm that the magnetic anisotropy is axial along the M-Dy-M axis and that the relaxation process occurs through the first excited energy level. Furthermore, the chromophoric [LH3]2- ligand is able to act as an 'antenna' group which was found to be effective in the selective sensitization of the emissions of TbIII-based complexes 3 and 6. The emission quantum yields and the luminescence lifetimes at room temperature are 11.7 % and 0.606 ms for 3, 22.7 % and 0.799 ms for 6

Capped Mesoporous Silica Nanoparticles for the Selective and Sensitive Detection of Cyanide

[EN] The development of easy and affordable methods for the detection of cyanide is of great significance due to the high toxicity of this anion and the potential risks associated with its pollution. Herein, optical detection of cyanide in water has been achieved by using a hybrid organic-inorganic nanomaterial. Mesoporous silica nanoparticles were loaded with [Ru(bipy)(3)](2+), functionalized with macrocyclic nickel(II) complex subunits, and capped with a sterically hindering anion (hexametaphosphate). Cyanide selectively induces demetallation of nickel(II) complexes and the removal of capping anions from the silica surface, allowing the release of the dye and the consequent increase in fluorescence intensity. The response of the capped nanoparticles in aqueous solution is highly selective and sensitive towards cyanide with a limit of detection of 2 mu M.We thank the Spanish Government (projects MAT2015-64139-C4-1-R and AGL2015-70235-C2-2-R (MINECO/FEDER, UE)) and the Generalitat Valenciana (project PROMETEOII/2014/047) for support.El Sayed, S.; Licchelli, M.; Martínez-Máñez, R.; Sancenón Galarza, F. (2017). Capped Mesoporous Silica Nanoparticles for the Selective and Sensitive Detection of Cyanide. Chemistry - An Asian Journal. 12(20):2670-2674. https://doi.org/10.1002/asia.201701130S267026741220Tylleskar, T., Howlett, W. P., Rwiza, H. T., Aquilonius, S. M., Stalberg, E., Linden, B., … Rosling, H. (1993). Konzo: a distinct disease entity with selective upper motor neuron damage. Journal of Neurology, Neurosurgery & Psychiatry, 56(6), 638-643. doi:10.1136/jnnp.56.6.638Johnson, J. D., Meisenheimer, T. L., & Isom, G. E. (1986). Cyanide-induced neurotoxicity: Role of neuronal calcium. Toxicology and Applied Pharmacology, 84(3), 464-469. doi:10.1016/0041-008x(86)90251-6Cyanide Toxicity 1991Jiang, J., Wang, X., Zhou, W., Gao, H., & Wu, J. (2002). Extraction of gold from alkaline cyanide solution by the tetradecyldimethylbenzylammonium chloride/tri-n-butyl phosphate/n-heptane system based on a microemulsion mechanism. Physical Chemistry Chemical Physics, 4(18), 4489-4494. doi:10.1039/b203467kGuidelines for drinking-water quality 2011Standard Methods for the Examination of Water and Wastewater 22nd ed 2012Suzuki, T., Hioki, A., & Kurahashi, M. (2003). Development of a method for estimating an accurate equivalence point in nickel titration of cyanide ions. Analytica Chimica Acta, 476(1), 159-165. doi:10.1016/s0003-2670(02)01362-4Safavi, A., Maleki, N., & Shahbaazi, H. . (2004). Indirect determination of cyanide ion and hydrogen cyanide by adsorptive stripping voltammetry at a mercury electrode. Analytica Chimica Acta, 503(2), 213-221. doi:10.1016/j.aca.2003.10.032Wang, F., Wang, L., Chen, X., & Yoon, J. (2014). Recent progress in the development of fluorometric and colorimetric chemosensors for detection of cyanide ions. Chemical Society Reviews, 43(13), 4312. doi:10.1039/c4cs00008kLin, W.-C., Fang, S.-K., Hu, J.-W., Tsai, H.-Y., & Chen, K.-Y. (2014). Ratiometric Fluorescent/Colorimetric Cyanide-Selective Sensor Based on Excited-State Intramolecular Charge Transfer−Excited-State Intramolecular Proton Transfer Switching. Analytical Chemistry, 86(10), 4648-4652. doi:10.1021/ac501024dWang, L., Zhu, L., & Cao, D. (2015). A colorimetric probe based on diketopyrrolopyrrole and tert-butyl cyanoacetate for cyanide detection. New Journal of Chemistry, 39(9), 7211-7218. doi:10.1039/c5nj01214gSingh, P., Mittal, L. S., Kumar, S., Bhargava, G., & Kumar, S. (2014). Perylene Diimide Appended with 8-Hydroxyquinoline for Ratiometric Detection of Cu2+ Ions and Metal Displacement Driven «Turn on» Cyanide Sensing. Journal of Fluorescence, 24(3), 909-915. doi:10.1007/s10895-014-1371-6Hong, K.-I., Yoon, H., & Jang, W.-D. (2015). A triazole-bearing picket fence type nickel porphyrin as a cyanide selective allosteric host. Chemical Communications, 51(35), 7486-7488. doi:10.1039/c5cc00809cBatista, R. M. F., Oliveira, E., Costa, S. P. G., Lodeiro, C., & Raposo, M. M. M. (2013). Cyanide and fluoride colorimetric sensing by novel imidazo-anthraquinones functionalised with indole and carbazole. Supramolecular Chemistry, 26(2), 71-80. doi:10.1080/10610278.2013.824082Gale, P. A., & Caltagirone, C. (2015). Anion sensing by small molecules and molecular ensembles. Chemical Society Reviews, 44(13), 4212-4227. doi:10.1039/c4cs00179fShiraishi, Y., Nakamura, M., Kogure, T., & Hirai, T. (2016). Off–on fluorometric detection of cyanide anions in an aqueous mixture by an indane-based receptor. New Journal of Chemistry, 40(2), 1237-1243. doi:10.1039/c5nj02873fBejoymohandas, K. S., Kumar, A., Sreenadh, S., Varathan, E., Varughese, S., Subramanian, V., & Reddy, M. L. P. (2016). A Highly Selective Chemosensor for Cyanide Derived from a Formyl-Functionalized Phosphorescent Iridium(III) Complex. Inorganic Chemistry, 55(7), 3448-3461. doi:10.1021/acs.inorgchem.5b02885Sancenón, F., Pascual, L., Oroval, M., Aznar, E., & Martínez-Máñez, R. (2015). Gated Silica Mesoporous Materials in Sensing Applications. ChemistryOpen, 4(4), 418-437. doi:10.1002/open.201500053El Sayed, S., Pascual, L., Licchelli, M., Martínez-Máñez, R., Gil, S., Costero, A. M., & Sancenón, F. (2016). Chromogenic Detection of Aqueous Formaldehyde Using Functionalized Silica Nanoparticles. ACS Applied Materials & Interfaces, 8(23), 14318-14322. doi:10.1021/acsami.6b03224Coll, C., Bernardos, A., Martínez-Máñez, R., & Sancenón, F. (2012). Gated Silica Mesoporous Supports for Controlled Release and Signaling Applications. Accounts of Chemical Research, 46(2), 339-349. doi:10.1021/ar3001469Ambrogio, M. W., Thomas, C. R., Zhao, Y.-L., Zink, J. I., & Stoddart, J. F. (2011). Mechanized Silica Nanoparticles: A New Frontier in Theranostic Nanomedicine. Accounts of Chemical Research, 44(10), 903-913. doi:10.1021/ar200018xAznar, E., Oroval, M., Pascual, L., Murguía, J. R., Martínez-Máñez, R., & Sancenón, F. (2016). Gated Materials for On-Command Release of Guest Molecules. Chemical Reviews, 116(2), 561-718. doi:10.1021/acs.chemrev.5b00456Pascual, L., Sayed, S. E., Martínez-Máñez, R., Costero, A. M., Gil, S., Gaviña, P., & Sancenón, F. (2016). Acetylcholinesterase-Capped Mesoporous Silica Nanoparticles That Open in the Presence of Diisopropylfluorophosphate (a Sarin or Soman Simulant). Organic Letters, 18(21), 5548-5551. doi:10.1021/acs.orglett.6b02793El Sayed, S., Giménez, C., Aznar, E., Martínez-Máñez, R., Sancenón, F., & Licchelli, M. (2015). Highly selective and sensitive detection of glutathione using mesoporous silica nanoparticles capped with disulfide-containing oligo(ethylene glycol) chains. Organic & Biomolecular Chemistry, 13(4), 1017-1021. doi:10.1039/c4ob02083aEl Sayed, S., Milani, M., Licchelli, M., Martínez-Máñez, R., & Sancenón, F. (2015). Hexametaphosphate-Capped Silica Mesoporous Nanoparticles Containing CuIIComplexes for the Selective and Sensitive Optical Detection of Hydrogen Sulfide in Water. Chemistry - A European Journal, 21(19), 7002-7006. doi:10.1002/chem.201500360Attia, S., Shames, A., Zilbermann, I., Goobes, G., Maimon, E., & Meyerstein, D. (2014). Covalent binding of a nickel macrocyclic complex to a silica support: towards an electron exchange column. Dalton Trans., 43(1), 103-110. doi:10.1039/c3dt51962gFabbrizzi, L., Licchelli, M., Manotti Lanfredi, A. M., Vassalli, O., & Ugozzoli, F. (1996). Template Synthesis of a Tetraaza Macrocycle Which Involves Benzaldehyde Rather Than Formaldehyde as a Building Block. Isolation and Structure Determination of the Open-Chain Schiff Base Intermediate Complex. Inorganic Chemistry, 35(6), 1582-1589. doi:10.1021/ic950841kBoiocchi, M., Licchelli, M., Milani, M., Poggi, A., & Sacchi, D. (2014). Oxo-Anion Recognition by Mono- and Bisurea Pendant-Arm Macrocyclic Complexes. Inorganic Chemistry, 54(1), 47-58. doi:10.1021/ic501527kFabbrizzi, L., Licchelli, M., Mosca, L., & Poggi, A. (2010). Template synthesis of azacyclam metal complexes using primary amides as locking fragments. Coordination Chemistry Reviews, 254(15-16), 1628-1636. doi:10.1016/j.ccr.2009.12.002Hinz, F. P., & Margerum, D. W. (1974). Ligand solvation and the macrocyclic effect. Nickel(II)-tetramine complexes. Inorganic Chemistry, 13(12), 2941-2949. doi:10.1021/ic50142a032El Sayed, S., Milani, M., Milanese, C., Licchelli, M., Martínez-Máñez, R., & Sancenón, F. (2016). Anions as Triggers in Controlled Release Protocols from Mesoporous Silica Nanoparticles Functionalized with Macrocyclic Copper(II) Complexes. Chemistry - A European Journal, 22(39), 13935-13945. doi:10.1002/chem.201601024Wang, L., Zhu, L., Li, L., & Cao, D. (2016). Tetraphenylethene-functionalized diketopyrrolopyrrole solid state emissive molecules: enhanced emission in the solid state and as a fluorescent probe for cyanide detection. RSC Advances, 6(60), 55182-55193. doi:10.1039/c6ra10073bWang, L., Li, L., & Cao, D. (2016). Dual binding site assisted chromogenic and fluorogenic discrimination of fluoride and cyanide by boryl functionalized BODIPY. 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Bis-tridentate Ir(III) Metal Phosphors for Efficient Deep-Blue Organic Light-Emitting Diodes

Emissive Ir(III) metal complexes possessing two tridentate chelates (bis-tridentate) are known to be more robust compared to those with three bidentate chelates (tris-bidentate). Here, the deep-blue-emitting, bis-tridentate Ir(III) metal phosphors bearing both the dicarbene pincer ancillary such as 2,6-diimidazolylidene benzene and the 6-pyrazolyl-2-phenoxylpyridine chromophoric chelate are synthesized. A deep-blue organic light-emitting diode from one phosphor exhibits Commission Internationale de l'Eclairage (CIE(x,y)) coordinates of (0.15, 0.17) with maximum external quantum efficiency (max. EQE) of 20.7% and EQE = 14.6% at the practical brightness of 100 cd m−2

Strong influence of the ancillary ligand over the photodynamic anticancer properties of neutral biscyclometalated IrIII complexes bearing 2‐benzoazole‐phenolates

In this paper, the synthesis, comprehensive characterization and biological and photocatalytic properties of two series of neutral IrIII biscyclometalated complexes of general formula [Ir(C^N)2(N^O)], where the N^O ligands are 2‐(benzimidazolyl)phenolate‐N,O (L1, series a) and 2‐(benzothiazolyl)phenolate‐N,O (L2, series b), and the C^N ligands are 2‐(phenyl)pyridinate or its derivatives, are described,. Complexes of types a and b exhibit dissimilar photophysical and biological properties. In vitro cytotoxicity tests conclusively prove that derivatives of series a are harmless in the dark against SW480 cancer cells (colon adenocarcinoma), but express enhanced cytotoxicity versus the same cells after stimulation with UV or blue light. In contrast, complexes of type b show a very high cytotoxic activity in the dark, but low photosensitizing ability. Thus, the ancillary N^O ligand is the main factor in terms of cytotoxic activity both in the dark and upon irradiation. However, the C^N ligands play a key role regarding cellular uptake. In particular, the complex of formula [Ir(dfppy)2(L1)] (dfppy=2‐(4,6‐difluorophenyl)pyridinate) [3 a] has been identified as both an efficient photosensitizer for 1O2 generation and a potential agent for photodynamic therapy. These capabilities are probably related to a combination of its notable cellular internalization, remarkable photostability, high photoluminescence quantum yield, and long triplet excited‐state lifetime. Both types of complexes exhibit notable catalytic activity in the photooxidation of thioanisole and S‐containing aminoacids with full selectivity.SpanishMinisteriode Econom&ayCompetitividad-FEDER(CTQ2014-58812-C2-1-Rand CTQ2014-58812-C2-2-R,CTQ2015-70371-REDT,CTQ2015-71353-R,CTQ2015-71154-P,and Unidadde Excelencia Mar&adeMaeztuMDM-2015-0538),the Conseje-r&adeEducacijn-Juntade CastillayLejn-FEDER(BU299A12-1,BU042U16and BU051U16).The Generalitat Valenciana(Prome-teo2016/135),andthe “la Caixa”Foundation(LCF/PR/PR12/11070003

Electrospun fluorescent nanofibers for explosive detection

Development of an instant on-site visual detection method for 2,4,6 trinitrotoluene (TNT) has become a significant requirement of the hour towards a secured society and a greener environment. Despite momentous advances in the respective field, a portable and reliable method for quick and selective detection of TNT still poses a challenge to many reasons attributing to inappropriate usage in subordinate areas and untrained personnel. The recent effort on the fluorescent based detection represents as one of easy method in terms of fast response time and simple on/off detection. Therefore, this chapter provides a consolidation of information relating to recent advances in fluorescence based TNT detection.Further, the main focus will be towards advances in the nanofibers based TNT detection and their reason to improving thesensitivity. © Springer International Publishing Switzerland 2015

Robust Deep-Red Emission in Iridium(III) Complexes Assisted by Ancillary Ligand for Solution-Processable Phosphorescent OLEDs

1