Stabilization of Luminescent Mononuclear Three-Coordinate CuI Complexes by Two Distinct Cavity-Shaped Diphosphanes Obtained from a Single α-Cyclodextrin Precursor.

Slightly different reaction conditions afforded two distinct cavity-shaped cis-chelating diphosphanes from the same starting materials, namely diphenyl(2-phosphanylphenyl)phosphane and an α-cyclodextrin-derived dimesylate. Thanks to their metal-confining properties, the two diphosphanes form only mononuclear [CuX(PP)] complexes (X=Cl, Br, or I) with the tricoordinated metal ion located just above the center of the cavity. The two series of CuI complexes display markedly different luminescence properties that are both influenced by the electronic properties of the ligand and the unique steric environment provided by the cyclodextrin (CD) cavity. The excited state lifetimes of all complexes are significantly longer than those of the cavity-free analogues suggesting peculiar electronic effects that affect radiative deactivation constants. The overall picture stemming from absorption and emission data suggests close-lying charge-transfer (MLCT, XLCT) and triplet ligand-centered (LC) excited states.

Stable Luminescent [Cu(NN)(PP)]+ Complexes Incorporating a ß-Cyclodextrin-Based Diphosphane Ligand with Metal-Confining Properties.

A ß-cyclodextrin-based diphosphane with metal-confining properties was efficiently synthesized thanks to an unprecedented Smiles-like rearrangement of diphenyl-(2-phosphanylphenyl)phosphane in the presence of excess n-BuLi. The cis-chelating bidentate ligand is capable of forming very stable heteroleptic [Cu(NN)(PP)]+ complexes in which a metal-bound diimine ligand (bpy, phen, or mmp) is located within the cyclodextrin cavity. As a result of ligand encapsulation, flattening of the metal tetrahedral geometry in the excited state is disfavored, thereby resulting in enhanced luminescent properties.

Rational Design of Mono- and Bi-Nuclear Cyclometalated Ir(III) Complexes Containing Di-Pyridylamine Motifs: Synthesis, Structure, and Luminescent Properties.

Heteroleptic cyclometalated iridium (III) complexes (1-3) containing di-pyridylamine motifs were prepared in a stepwise fashion. The presence of the di-pyridylamine ligands tunes their electronic and optical properties, generating blue phosphorescent emitters at room temperature. Herein we describe the synthesis of the mononuclear iridium complexes [Ir(ppy)2(DPA)][OTf] (1), (ppy = phenylpyridine; DPA = Dipyridylamine) and [Ir(ppy)2(DPA-PhI)][OTf] (2), (DPA-PhI = Dipyridylamino-phenyliodide). Moreover, the dinuclear iridium complex [Ir(ppy)2(L)Ir(ppy)2][OTf]2 (3) containing a rigid angular ligand "L = 3,5-bis[4-(2,2'-dipyridylamino)phenylacetylenyl]toluene" and displaying two di-pyridylamino groups was also prepared. For comparison purposes, the related dinuclear rhodium complex [Rh (ppy)2(L)Rh(ppy)2][OTf]2 (4) was also synthesized. The x-ray molecular structure of complex 2 was reported and confirmed the formation of the target molecule. The rhodium complex 4 was found to be emissive only at low temperature; in contrast, all iridium complexes 1-3 were found to be phosphorescent in solution at 77 K and room temperature, displaying blue emissions in the range of 478-481 nm.

Enantiopure, luminescent, cyclometalated Ir(III) complexes with N-heterocyclic carbene-naphthalimide chromophore: design, vibrational circular dichroism and TD-DFT calculations.

A series of chiral cyclometalated iridium complexes of the type [Ir(C^N)2(C^C:)], {(C^N) = ppy (2); dfppy (3)} featuring a naphthalimide N-heterocyclic carbene ligand (C^C:) = (Naphthalimide-NHC) are described and fully characterized. The racemic complexes rac-2 and rac-3 were resolved via chiral column chromatography techniques into their corresponding enantiopure species Δ-2, Λ-2, Δ-3, Λ-3 as confirmed by their CD curves. This unique class of molecules containing organic and inorganic chromophores might be used as a platform to probe the stereochemical effect on the photophysical properties. Vibrational circular dichroism (VCD) was used as an important tool to assign successfully the stereochemistry of the enantiomers. TD-DFT calculations are also advanced to support the experimental studies and to rationalize the observed results.

Efectos del ruido en la calidad vocal de docentes de instituciones educativas / Effects of noise on the vocal quality of educational institute teachers

Introducción: la investigación tuvo como objetivo identificar el efecto del ruido en la calidad vocal mediante el análisis acústico de la voz en docentes de instituciones educativas en Cúcuta, Norte de Santander. Métodos: se llevó a cabo un estudio descriptivo de enfoque cuantitativo, con una población total de 71 docentes, a quienes se les realizó: audiometría, análisis acústico de la voz, protocolo índice de incapacidad vocal y sonometría. Resultados: se encontró un promedio de ruido para cada área entre 62 y 65 dB y se identificó alteración en JITTER local a 25 docentes de los 57 evaluados. JITTER =0,307+0,015 edad-0,126 sexo-0,012 tiempo de servicio +0,018 horas trabajadas -0,008 ruido Análisis y discusión: en modelos de regresión el resultado fue R2=18,6% lo cual indica que, en conjunto, las variables independientes explican en un 18,6% la varia-bilidad que se presenta en la variable dependiente, JITTER. A pesar de que esta ecuación no es la mejor para fines predictivos, las relaciones que obtuvimos están en correspondencia con los postulados teóricos de la voz. Conclusiones: no hubo variabilidad en las mediciones del ruido. Sus porcentajes fueron homogéneos, esto impidió realizar un registro predictivo con el modelo de regresión. Sin embargo, la literatura indica que el ruido es un factor significativa-mente influyente en la calidad vocal cuando se ve acompañado de otros factores de exposición

Introduction: the objective of this research was to identify noise effect on vocal quality through acoustic analysis of the voice of teachers who work in educational institutions in Cúcuta, Norte de Santander. Methods: a descriptive study with a quantitative approach was carried out with a total po-pulation of 71 teachers, who underwent: audiometry, acoustic analysis of the voice, vocal disability index protocol and sonometry.Results: the average noise level found for each area ranged between 62 and 65 dB and an alteration in local JITTER in 25 of the 57 teachers evaluated was discovered. JITTER = 0.307 + 0.015 age-0.126 sex-0.012 service time +0.018 hours worked -0.008 noise. Analysis and discussion: in the regression models the result was R2 = 18.6%, which indica-tes that, as a whole, the independent variables explain 18.6% of the variability that occurs in the dep endent variable, JITTER. Although this equation is not the best for predictive purposes, the relationships we obtained are in correspondence with the voice theoretical postulates. Conclusions: there was no variability in noise measurements. Their percentages were ho-mogeneous, which prevented a predictive registration with the regression model. However, according to literature noise is a factor that significantly influences vocal quality as long as it is accompanied of other exposure factors.