Elena Lucenti

Italian National Research Council | CNR · SCITEC

Stimuli responsive luminescent materials possessing room temperature phosphorescence (RTP) are extremely desirable for various applications. The here investigated derivative of cyclic triimidazole (TT) functionalized with carbazole (Cz), namely TT-Ph-Cz, belongs to this class. TT-Ph-Cz possesses high conformational freedom resulting in rigidochromi...

The coordination ability of the pyridine derivative of cyclic triimidazole, namely 3-(pyridin-2-yl)triimidazotriazine (TT-Py) towards Cu(I) was explored. TT-Py is an appealing nitrogen-rich ligand characterized by the presence of three imidazole nitrogen atoms with trigonal symmetry and a pyridine moiety, available for coordination to metal ions. T...

The development of organic room-temperature phosphorescent (ORTP) materials represents an active field of research due to their significant advantages with respect to their organometallic counterparts. Two cyclic triimidazole (TT) derivatives bearing one and three hexyl-thiophene moieties, TT-HThio and TT-(HThio)3, have been prepared and characteri...

The synthesis and characterization of a small series of cyclic triimidazole derivatives functionalized with methylated pyridine or guanidine moieties is reported. These compounds were tested for their ability to bind to G‐quadruplexes from both telomeric and oncogene promoter sequences. Some of them exhibited high affinity and effective G‐quadruple...

Two derivatives of cyclic triimidazole and pyrene, namely the blue emitting 3-(pyren-1-yl)triimidazo[1,2-a:1′,2′-c:1″,2″-e] [1,3,5]triazine, TTPyr, and the yellow-orange emitting 11-(pyren-1-yl)triimidazo[1,2-a:1′,2′-c:1″,2″-e] [1,3,5]triazine-3,7-dicarbaldehyde, (CHO)2TTPyr, are here exploited for titration experiments with various nitroaromatic e...

A QTAIM and IQA investigation on model compounds of two isostructural Ag I and Cu I coordination polymers (CPs) based on cyclic triimidazole ( L ), i.e. the [ M I L ] n 1D double-stranded stair chain and the [ M Cl L ] n 3D network ( M = Cu, Ag), has allowed light to be shed on the different emissive behaviour associated with the two metal ions. Ac...

Tris(pentafluorophenyl)silanol (C6F5)3SiOH was prepared from the corresponding chlorosilane (C6F5)3SiCl by an unconventional controlled hydrolysis. The X-ray structure and the reactivity of the new silanol with various bases, with triflic acid and with some rhenium carbonyl complexes are reported. The Si-C6F5 bond is easily cleaved in the presence...

Anti-Kasha behavior has been the subject of intense debate in the last few years, as demonstrated by the high number of papers appearing in the literature on this topic, dealing with both mechanistic and applicative aspects of this phenomenon. Examples of anomalous emitters reported in the last 10 years are collected in the present review, which is...

The search of new organic emitters is receiving a strong motivation by the development of ORTP materials. In the present study we report on the preparation, optical and photophysical characterization, by both steady state and time resolved techniques, of two pyrene-functionalized cyclic triimidazole derivatives. Together with the already reported m...

Organic materials with multiple emissions tunable by external stimuli represent a great challenge. TTPyr, crystallizing in different polymorphs, shows a very rich photophyisics comprising excitation‐dependent fluorescence and phosphorescence at ambient conditions, and mechanochromic and thermochromic behavior. Transformation among the different spe...

Purely organic luminophores that exhibit room temperature phosphorescence (RTP) are receiving an ever growing attention. The design of efficient RTP materials and the understanding of their emissive behaviour, however, remain a challenging task. Herein, to gain further insights into metal‐free RTP, we report the synthesis, characterization and phot...

Eight Cu(II) coordination compounds with cyclic triimidazole, triimidazo[1,2-a:1’,2’-c:1”,2”-e][1,3,5]-triazine (L1), its positional isomer, triimidazo[1,2-a:1’,2’-c:1”,5”-e][1,3,5]-triazine (L2), and two pyridine derivatives of L1, 3-(pyridin-2-yl)triimidazo[1,2-a:1',2'-c:1'',2''-e][1,3,5]triazine (L3) and 3-(pyridin-4-yl)triimidazo[1,2-a:1',2'-c:...

The remarkable emissive properties of cyclic triimidazole (TT), showing crystallization-induced emissive behavior and, in particular, room temperature phosphorescence (RTP), are here combined with its versatility in assembling coordination compounds. A series of Ag(I) coordination polymers (CPs), comprising a 1D chain ([Ag(TT)I]n, 1-Ag) and 3D netw...

Novel fumaramides exhibit room-temperature phosphorescence in the solid state once molecular design and positioning of the carbonyl and bromine atoms allow for the formation of strong intermolecular halogen bonding interactions.

The development of purely organic materials showing multicolor fluorescent and phosphorescent behaviour represents a formidable challenge in view of practical applications. Herein the rich photophyisical behaviour of 3-(pyridin-2-yl)triimidazotriazine (TT-Py) organic molecule, comprising excitation-dependent fluorescence and phosphorescence under a...

Organic room temperature persistent luminescence is a fascinating but still largely unexplored phenomenon. Cyclic-triimidazole and its halogenated (Br, I) derivatives have recently revealed as intriguing phosphors characterized by multifaceted emissive behavior including room temperature ultralong phosphorescence (RTUP) associated with the presence...

A family of cyclic triazines, based on the triimidazo[1,2-a:10,20-c:100,200-e][1,3,5]triazine scaffold, has recently caught attention due to its variegated solid state photoluminescent properties (e.g., crystallization induced emission, fluomechanochromism, dual fluorescence, room temperature ultralong phosphorescence), tuned by proper functionaliz...

The linear and second-order nonlinear optical (NLO) properties of two pyrene-pyridine chromophores, namely, 4-(pyren-1-yl)pyridine (L1) and 4-(2-(pyren-1-yl)ethyl)pyridine (L2), were investigated and modulated by performing protonation/deprotonation cycles or by complexation to d10 metal centers such as Zn(II) and Cu(I) to form the monomeric [Zn(CH...

Cyclic triimidazole (C9H6N6, L), with C3h molecular symmetry and three nitrogen atoms available for coordination, is here successfully employed for the first time in the synthesis of coordination compounds. In particular, by varying the reaction conditions (e.g. solvent, temperature, template), seven Cu(I)-halide coordination polymers of different...

Four coordination compounds [Zn3(CH3COO)6(H2O)2](TT)2 [Cd(H2O)6](ClO4)2(TT)2, [Cd(H2O)6](BF4)2(TT)2, [Zn(H2O)6](BF4)2(TT)2 (1‐4) accommodating the crystallization induced emissive triimidazo[1,2‐a:1’,2’‐c:1’’,2’’‐e][1,3,5]triazine (TT) as a guest in their crystal lattice are isolated and fully photophysically and structurally characterized. Their e...

Since heavy halogen atoms can be used to tune the emissive properties of organic luminogens, the understanding of their role in the photophysics is fundamental for materials engineering. Here, the extrinsic and intrinsic heavy atom effects on the photophysics of organic crystals are separately evaluated by comparing cyclic triimidazole (TT) with it...

Solid state organic compounds, endowed with enhanced emission, have been gaining great attention in the scientific community for their potential application in different areas, such as lighting technologies or bioimaging. In this field, mono‐ and di‐bromo derivatives of triimidazo[1,2‐a:1',2'‐c:1”,2”‐e][1,3,5] triazine have been proposed as new org...

The understanding of the mechanisms involved in crystal packing effects on the photophysical properties of a molecular entity is fundamental to engineer solid materials for specific applications. In fact, besides rigidification and protection from oxygen quenching, crystal packing influences the emissive properties through specific interactions. In...

Purely organic materials showing solid state room temperature phosphorescence (RTP) are receiving an ever growing interest due to their low toxicity, cost and environmental load with respect to their organometallic counterparts. In addition, specific features potentially associated with organic phosphorescent materials, such as long afterglow lifet...

Solid luminogens' performances are determined by both their inherent electronic properties and packing status. Intermolecular interactions have been exploited to produce persistent room-temperature phosphorescence (RTP) from organic molecules. However, the design of organic materials with bright RTP and the rationalization of the role of interchrom...

Solid luminogens' performances are determined by both their inherent electronic properties and packing status. Intermolecular interactions have been exploited to produce persistent room-temperature phosphorescence (RTP) from organic molecules. However, the design of organic materials with bright RTP and the rationalization of the role of interchrom...

The second-order nonlinear optical (NLO) properties of two tetrathiafulvalene (TTF)-fused electron donor–acceptor dyads have been determined by Electric Field Induced Second Harmonic generation (EFISH) technique and theoretically rationalized. Dyads TTF-dppz (1) and TTF-BTD (2) were obtained by direct fusion of a TTF electron donor unit either with...

Solid state luminescent materials with long lifetimes are the subject of ever growing interest both from a scientific and a technological point of view. However, when dealing with organic compounds, the achievement of highly efficient materials is limited by aggregation caused quenching (ACQ) phenomena on one side and by ultrafast deactivation of t...

A novel and versatile approach to tune photoluminescence and electroluminescence by in situ controlled thermal deprotonation is presented. This methodology, based on a single organic π-conjugated material (pyrene derivative), allows the manufacturing of Organic Light-Emitting Diodes (OLEDs) prototypes by solution methods with controlled tunable emi...

The synthesis and characterization of three 5-π-delocalized-donor-1,3-di(2-pyridyl)benzenes is reported along with that of their related cyclometallated platinum(ii) complexes and N,N-dimethylated iodide salts. The second-order nonlinear optical (NLO) properties of all the compounds have been determined by the Electric Field Induced Second Harmonic...

Inorganic-organic hybrid materials have shown excellent optoelectronic device performances from single-layer solution-processed thin films. Their electronic bands are coupled to the ionic interactions within the organic and inorganic moieties. Exactly these features also allow a sequential deposition route so as to implement thin films having inher...

The continuous search for hybrid inorganic-organic compounds to be used in a variety of applications points obviously to the abundant, cheap, and environmental friendly copper. Cu(I) complexes exhibit a high structural diversity and are emissive with several classes of ligands with properties varying markedly with structure and environment. Solid s...

The unexpected and acido-triggered reversible luminescent and nonlinear optical properties of (2-pyrene-1-yl-vinyl)pyridine, a simple and highly transparent chromophore, are studied both in solution and in the solid state. Remarkably, for the first time the acidomodulation of the NLO response of a poled thin film is reported.

A poly(methyl methacrylate) (PMMA) composite film containing 4 wt% of the strongly second order NLO active ionic material [(E)-N,N-dimethylamino-N’-methylstilbazonium][p-toluenesulfonate] (DAST) deposited on ITO substrate shows by a two step process (electric poling followed by controlled thermal annealing) a nonlinear optical coefficient d33 highe...

Owing to their low glass transition temperature, Tg, amorphous thin films of N,N′-bis(3-methylphenyl)-N,N′-bis(phenyl)benzidine (TPD) undergo morphological changes even at room temperature. It has been noticed previously that exposure to UV light can increase apparent Tg of TPD films and thus stabilize their morphology. However, the reason behind i...

Diphenyl-(4-{2-[4-(2-pyridin-4-yl-vinyl)-phenyl]-vinyl}-phenyl)-amine (DPVPA) constitutes a novel acido-triggered reversible luminescent and nonlinear optical switch. Remarkably, for the first time the Electric-Field Induced Second Harmonic generation (EFISH) technique is used to reveal a protonation-deprotonation NLO contrast.

Solid state luminescent materials are the subject of ever growing interest both from a scientific and a technological point of view because high-tech applications of light emitting materials very often require their use in the condensed phase. Aggregation caused quenching processes however represent an obstacle to the development of most luminogens...

The synthesis and catalytic activity of some new titanium(IV) complexes with incompletely condensed Cy6Si6O7(OH)4 and endo-Cy8Si8O11(OH)2 (Cy = c-C6H11) silsesquioxane cages have been carried out with the aim of investigating new Ti silsesquioxane frameworks as molecular models of titanium active sites of catalysts prepared by grafting Ti(IV) precu...

The reactivity of [Re(CO)5Cl] and [Re2(CO)10] with nucleophiles such as Me3SiO− and MeO− has been investigated by low-temperature NMR and by infrared spectroscopy particularly aimed at detecting the [Re(CO)5OR] species, which so far have eluded isolation, proposed as intermediates in the synthesis of the dimeric species [Re2(CO)6(μ-OR)3]− (R = SiMe...

{Reactions of [Re(2)(CO)(8)(THF)(2)] with various silsesquioxanes ([(c-C(6)H(11))(7)Si(8)O(12)(OH)] (1), [(c-C(6) H(11))(8)Si(8)O(11)(OH)(2)] (2), and endo-[(c-C(6)H(11))(8)Si(8)O(11)(OH)(2)] (3)), which mimic different kinds of silanol sites of the silica surface, afford new molecular models of the silica-anchored [Re(2)(CO)(8)(mu-H)(mu-OSi )] sur...

IntroductionSynthesis of neutral osmium carbonyl clustersSynthesis of anionic osmium carbonyl clustersThe understanding of the process of nucleation of surface osmium(II) carbonyl species to osmium carbonyl clustersConclusion

A series of sodium arylcyclotetrasiloxanolates properly functionalized in the para position of the aromatic ring, like [4-RC6H4Si(O)ONa]4 and the corresponding (trimethylsiloxy)cyclotetrasiloxanes [4-RC6H4Si(O)OSiMe3]4 (R=Cl, Br, CHCH2, CH2Cl), were prepared as scaffolds for anchoring second order NLO active or fluorescent organic chromophores. Suc...

The reactions of [Os3(CO)10(μ-H)(μ-OH)] (3) with the incompletely condensed silsesquioxanes [(c-C6H11)7Si7O9(OH)3] (1) and [(c-C6H11)8Si8O11(OH)2] (2) afford in high yield {Os3(CO)10(μ-H)[(μ-O)Si7O10(c-C6H11)7]} (4) and the new compounds {Os3(CO)10(μ-H)[(μ-O)Si7O9(OH)2(c-C6H11)7]} (5), {[Os3(CO)10(μ-H)]2(μ-O)2Si7O9(OH)(c-C6H11)7} (6), {Os3(CO)10(μ-...

Reaction of Re(CO)5O3SCF3 with (c-C6H11)7Si8O12O-Li+ at 273 K under a CO atmosphere affords the [Re(CO)5OR] (R = (c-C6H11)7Si8O12) derivative (1). 1 is the first example of a rhenium pentacarbonyl bearing an OR ligand (R = alkyl, aryl, or silyl) stable enough to be characterized, and it represents also the first molecular model of the surface [Re(C...

Reaction of Me3SiONa with [Re(CO)(5)Cl] affords the new complex Na[Re-2(CO)(6)(mu-OSiMe3)(3)], which could be generated via formation of [Re(CO)(5)OSiMe3] followed by immediate reaction with Me3SiO-. Substitution of some CO ligands by phosphines significantly decreases the electrophilicity of the Re(I) center, and therefore hinders further attack b...

Coordination to the “Os3(CO)11” cluster core of substituted styrylpyridines such as trans-4-(4‘-NMe2-styryl)pyridine (L1), trans-4-(4‘-t-Bu-styryl)pyridine (L2), trans-4-(4‘-CF3-styryl)pyridine (L3), or trans,trans-4-(4‘-NMe2-phenyl-1,3-butadienyl)pyridine (L4) produces an enhancement of their quadratic hyperpolarizability, βEFISH, measured by the...

This review covers the innovative and promising area of syntheses of metal carbonyl complexes and clusters mediated by the surface of inorganic oxides. Emphasis is placed on syntheses which allow comparison of yields and reaction conditions with respect to traditional syntheses in solution. The use of the silica surface is described first, followed...

The hydrides localisation in the hydrido carbonyl cluster [H5Os10(CO)24]−, obtained in excellent and reproducible yields by hydrogenation (1 atm, 200°C) of silica-supported [Os(CO)3(OH)2]n, has been investigated by variable temperature 1H NMR and X-ray diffraction of the [(Ph3P)2N]+ salt. Using both stereochemical and potential energy consideration...

Various osmium species (e.g. Na2[Os10C(CO)24], OsCl3·nH2O and [Os(CO)3Cl2]2) are able to activate acetonitrile towards nucleophilic attack by water to give acetamide. The most efficient catalyst appears to be [Os(CO)3Cl2]2, which gives good yields of acetamide by working in air at 76°C. An increase of the quantity of water has a positive effect on...

The reductive carbonylation under 1 atm of CO of [Rh(CO)2Cl]2 supported on a silica surface added with a base such as CH3CO2Na, Na2CO3 or K2CO3, can be directed toward the formation of [Rh4(CO)12], [Rh6(CO)16] or K2[Rh12(CO)30] by controlling (i) the nature and amount of base; (ii) the amount of surface water; (iii) the reaction time; (iv) the temp...

[Ru3(CO)12], [H4Ru4(CO)12], and [Ru6C(CO)16]2− have been synthesized in reproducible high yields and under mild conditions (1 atm) by a two-step methodology involving (i) first carbonylation of RuCl3·nH2O dissolved in ethylene glycol to give a mixture of tri- and di-carbonyl ruthenium(II) species, probably of the kind [Ru(CO)3Cl2(ethylene glycol)]...

Coordination to Zn(II) of 5-X-1,10-phenanthrolines (X = electron donor) produces a significant enhancement of their quadratic hyperpolarizability, in contrast to the case for coordination to Cd(II). In Zn(II) and Pt(II) complexes carrying two trans-4-(dimethylamino)-4‘-stilbazoles in a tetrahedral or planar coordination, coordination induces a limi...

The reactivity (e.g., toward hydrolysis, alcoholysis, reduction by CO or H2) of various [Os3(CO)10(μ-H)(μ-OSiPh2R‘)] (R‘ = Ph, OH, OSiPh2OH) clusters and the thermal behavior of [Os3(CO)10(μ-H)(μ-OSiEt3)] have been studied with the aim of clarifying by a molecular approach some aspects of the surface chemistry of silica-anchored [Os3(CO)10(μ-H)(μ-O...

New high yield routes to the high nuclearity hydrido carbonyl clusters [H5Os10(CO)24]- and [H4Os10(CO)24]2-, model systems for the chemisorption of CO and H2 on metal surfaces, are reported. [H5Os10(CO)24]- is obtained in good yields by hydrogenation (1 atm) at 200C of physisorbed [Os(CO)3(OH)2]n whereas in refluxing ethylene glycol solution, that...

The easy replacement of the hydroxy ligand in [Os3(CO)10(μ-H)(μ-OH)] by siloxy ligands affords a high-yield procedure to model compounds of the type [Os3(CO)10(μ-H)(μ-OSiR2R′)] (R = Et, Ph; R′ = Et, Ph, OH, OSiPh2OH), a springboard to better understand the reactivity of osmium carbonyl species on the silica surface. The new clusters [Os3(CO)10(μ-H)...

The easy replacement of the hydroxy ligand in [Os3(CO)10(μ-H)(μ-OH)] by siloxy ligands affords a high-yield procedure to model compounds of the type [Os3(CO)10(μ-H)(μ-OSiR2R‘)] (R = Et, Ph; R‘ = Et, Ph, OH, OSiPh2OH), a springboard to better understand the reactivity of osmium carbonyl species on the silica surface. The new clusters [Os3(CO)10(μ-H)...

[M3(CO)12], [H4M4(CO)12], [H3M4(CO)12]− (MRu, Os) and [Ru6C(CO)16]2− have been synthesized in high yields by one-pot controlled reduction at atmospheric pressure of MCl3 or [M(CO)3Cl2]2, dissolved in t-amyl alcohol or ethylene glycol, working in the presence of alkali carbonates. The selectivity of the reduction is controlled by the: (i) nature an...

Activation of [Os3(CO)12] by the silica surface via reaction with surface silanol groups provides a new convenient general approach to the selective, high-yield synthesis of various osmium carbonyl clusters such as [H4Os4(CO)12] and [HOs3(CO)10Y] (Y = a three-electron donor such as OH, OR, Cl, Br, I, O2CR, and SCN). These silica-mediated syntheses...

[Ru3(CO)10Cl2], [Ru3(CO)12], [H4Ru4(CO)12], [H3Ru4(CO)12]-, [HRu6(CO)18]-, and [Ru6C(CO)16]2- have been synthesized in good or high yields by one-step or two-step (with the surface species [Ru(CO)3Cl2(HOSi)] as intermediate) one-pot controlled reduction of RuCl3 supported on silica in the presence of alkali carbonates. The selectivity of the reacti...

A high-yield procedure is described for the preparation, from [M(CO)3Cl2]2 (M = Ru, Os) and aqueous NaOH, of the new water-soluble and air-stable species [Ru(CO)2Cl(OH)]n, [Ru(CO)2(OH)2]n, [Os(CO)3Cl(OH)]2, and [Os(CO)3(OH)2]x (x = 2 or n).