Conjugated donor-acceptor molecules are the focus of research owing to their unusual photo- and electro-physical properties. At the same time, several unusual features of these compounds are difficult to explain or predict. Here we present our results on the synthesis, X-ray structures and D-NMR spectra providing a deeper insight into the conjugation within the derivatives involving the 1,3-indandione-derived series of compounds with varying electron acceptor strength and conjugating bridge length. The X-ray structures show the presence of several intermolecular short contacts strongly affecting the molecular geometries. In solution, the coalescence temperatures corresponding to the rotation of the phenylamino moiety of all derivatives do not exceed 246 K indicating the unhindered rotation at room temperature. Using B3LYP/aug-cc-pVDZ, the calculated model chemistry barriers to rotation, dipole moments and first hyperpolarizabilities are within experimental error. We conclude that neglecting the electron donating properties of bridges themselves and internal rotation about the single bonds taking part in conjugation can result, for instance, in misinterpretation of their room temperature NMR spectra and overestimation of the computed molecular dipole moments by more than 5 D.

Oxidative stress and inflammation accompanying hypertension serve as independent risk factors for endothelial dysfunction underlying accelerated atherosclerosis. Priming of polymorphonuclear leukocytes (PMNLs) contributes to oxidative stress and inflammation, preceding the rise in blood pressure in Sabra hypertension-prone rats. While the vast majority of studies have focused on vascular NADPH oxidase as the main culprit underlying oxidative stress and inflammation in hypertension, this study was aimed to elucidate the contribution of phagocytic NADPH oxidase in the pathophysiology of hypertension. Sabra salt sensitive (SBH/y) and salt resistance (SBN/y) rats were Salt loaded for 60 days. In parallel, phenylarsine oxide (PAO), an NADPH oxidase inhibitor, was injected every 48 hours to the experimental groups (SBH/y+/+; SBN/y+/+), whereas the vehicle polyethylene glycol 200 was injected to the control groups (SBH/y+/-; SBH/y+/-). Systolic BP was monitored throughout the experiment. PMNL priming was assessed by the rate of superoxide release and by CD11b intensity measured by flow cytometry. PMNL counts served as a marker for inflammation. Salt loading induced an elevation of BP in the SBH/y+/- group, which was completely inhibited by PAO in SBH/y+/+, concomitantly with inhibition of the augmented rate of superoxide release, increase in PMNL surface CD11b and the elevation in PMNL counts, otherwise observed in SBH/y+/-. PAO administration did not alter the total urinary sodium excretion. Primed PMNLs play an important role in the development of hypertension via activation of their NADPH oxidase. See Table 1.

This study characterizes the causal relationship between peripheral polymorphonuclear leukocyte (PMNL) priming, systemic oxidative stress (OS), and inflammation in patients with varying degrees of renal insufficiency (chronic kidney disease [CKD] not on renal replacement therapy [RRT]: continuous ambulatory peritoneal dialysis or hemodialysis [HD]) and healthy control subjects. Rate of superoxide release was measured after stimulation of PMNL with phorbol 12-myristate 13-acetate or zymosan. Priming was estimated by the rate of superoxide release after phorbol 12-myristate 13-acetate stimulation. Systemic OS was related to PMNL priming and intracellular myeloperoxidase activity. Inflammation was linked to peripheral white blood cells and PMNL counts, PMNL apoptosis, and PMNL ex vivo survival in autologous and heterologous sera. PMNL priming and counts were related to the severity of renal failure in CKD not on RRT. Compared with control subjects, PMNL from all CKD patients showed increased priming, highest in HD, with a significant decrease in their response to zymosan. PMNL myeloperoxidase activity and apoptosis were increased in all renal failure patients. Decreased ex vivo cell survival and elevated leukocyte counts were found in all patients, highest in HD. Both PMNL priming and counts correlated negatively with the GFR. A positive significant correlation was shown between PMNL counts and their priming in all groups, suggesting that the increased PMNL count in peripheral blood is an adaptive response to PMNL priming. Hence, PMNL priming is a key mediator of low-grade inflammation and OS associated with renal failure, occurring before the onset of RRT and further augmented in chronic HD.

Hypertension is accompanied by systemic oxidative stress, inflammation, and priming of peripheral polymorphonuclear leukocytes (PMNLs), yet the involvement of these factors in the pathophysiology of hypertension is incompletely understood. We investigated the relationship between oxidative stress, primed PMNLs, and inflammation and the development of hypertension in the Sabra rat model of salt-sensitive hypertension. Sabra hypertension-resistant rats (SBN/y) (salt-resistant) and Sabra hypertension-prone rats (SBH/y) (salt-sensitive) were studied under normal conditions or during salt loading. Systolic blood pressure (BP) was measured by the tail-cuff method. The extent of oxidative stress was evaluated by the rate of superoxide release from PMNLs, plasma-reduced glutathione (GSH) levels, malondialdehyde (MDA) levels (estimated by thiobarbituric acid-reacting substances), and plasma-carbonylated fibrinogen (Western blotting). Plasma fibrinogen levels and the peripheral PMNL count served as indices of inflammation. In SBH/y and SBN/y provided regular chow without salt loading, BP did not rise above baseline values, yet superoxide release, plasma MDA, carbonylated fibrinogen, and PMNL count were higher in SBH/y than in SBN/y, whereas GSH levels were lower in SBH/y. Four weeks of salt loading resulted in a gradual increase in systolic BP in SBH/y to 205+/-3 mm Hg, whereas BP remained in SBN/y at baseline normotensive levels. All the parameters reflecting oxidative stress and inflammation were further aggravated with the development of hypertension in salt-loaded SBH/y. We conclude that primed PMNLs, oxidative stress, and inflammation antecede the development of hypertension in this experimental model of hypertension.

C 2 6Hi2N 8 Oi6, monoclinic, C12/cl (No. 15), a = 12.295(2) Â, b = 10.657(2)Â, c = 20.763(3)Â, β = 94.308(7)°,V = 2712.8Â 3 , Z = 4, Rgt(F) = 0.105, wRretiF 2 ) = 0.353, T= 295 K.

Electron donor-pi -acceptor chromophores 5, 9, 11, 18-20, 21, 22, 27, 28a, 28c, 31, 32, 34-36, 38a-c, 41a, 41c, and 42 have been synthesised. The donor units are 1,3-dithiole and ferrocene; conjugated ethylenic, phenyl, phenylenevinylene, thienyl, bithienyl, terthienyl, or thienylenevinylene linkers act as a central pi -electron relay unit, and dicyanomethylene and polynitrofluorene groups as the acceptor unit. The electronic absorption spectra display a broad low-energy intramolecular charge transfer band in the visible region (500-700 nm) the energy (hv(1CT) approximate to 1.7-2.5eV) and intensity (epsilon approximate to 5000-50000 m(-1)cm(-1)) of which depend substantially on the nature of both D and A moieties and on the structure of the linker unit. Nonlinear optical properties have been evaluated using the EFISH technique: the highest mu beta (0) values are observed for 38b [(900 +/- 300)x10(-48) esu] and 42 [(1800 +/- 300)x10(-48) esu] establishing that polynitrofluorene is a promising acceptor terminal moiety in this context. The molecular and electronic structures of 49 and 50 have been calculated by the RHF/6-31G(d)//RHF/6-31G(d) ab initio method. The HOMO is located mostly in the 1,3-dithiolium ring, and the LUMO mostly at the dicyanomethylene fragment (and the phenyl ring of 50) although the population at C2 of the 1,3-dithiolium rings is also considerable. The X-ray crystal structures of 9, 18 and 27 are reported. In all three structures the conjugated pi -systems effectively planar with extensive pi -electron delocalisation between the donor and acceptor moieties, The planar conformation of 18 gives rise to a close intramolecular S . . .S contact of 3.095(3) Angstrom between the dithiole and thiophene units.

We study 2-(p-N-hexadecyl-N-methylamino)benzylidene-1,3-indandione (1a) as a model compound for the preparation of nonlinear optically (NLO) active Langmuir-Blodgett (LB) layers. The pressure-area (pi -A) isotherm of (1a) at the air-water interface is investigated. A limiting area of 0.60 +/- 0.02 nm(2) per molecule is found. The alternate-layer LB deposition of compound (la) and an inert spacer, cadmium stearate, at different surface pressures is performed. The effects of temperature and delay time between spreading of the Langmuir film and the deposition of the LB films are studied. An increase of collapse pressure from 20 to 30 mN/m is observed as the delay time increases. UV-vis spectra indicate a uniform transfer of (la) and show compression-induced changes as a function of the deposition conditions. A split of the absorption maximum is observed for LB films deposited at higher pressures and lower temperatures. The two bands can result from two different molecular electronic transitions, affected by the aligning influence of the surface, and the different environments in the film compared to solution. Alternatively, these two bands can be associated with (at least) two different conformers. The orientation of the transition moments is evaluated on the basis of polarized UV-vis spectra at different angles of incidence, and found to be 40-44 degrees. Significant second harmonic (SH) generation by the LB films is observed. Analysis of the SH response gives a tilt angle of 44 degrees, in agreement with the finding from UV absorbance.

The second order nonlinearity (beta) was measured for several structurally similar organic pi -conjugated molecules. A unique transition from "1-dimensional" to "2-dimensional" behavior is observed for molecules containing the carbazole donor group. These "2-D" molecules exhibit two beta components which are detected by a combination of coherent and incoherent experimental techniques. Another aspect reported is the dependence of beta on the frequency; the resonance enhancement of carbazole molecules with two beta components is much larger than for the 1-D molecules.

The second order nonlinearity (beta) of a series of organic pi -conjugated molecules involving 1,3 indandione derivatives as an acceptor moiety has been measured. The effect of varying the donor from dialkylamino to N-carbazolyl substituents was examined. Despite the chemically similar nature of the two donors, a drastic reduction of electric field induced second harmonic (EFISH) beta values for the molecules involving the N-carbazolyl substituents was detected. Quantum mechanical calculations indicate that the decrease in beta values results from the presence of two overlapping transitions that contribute to beta with opposite signs. Thus, the charge transfer band gives a positive beta (zzz) contribution along the long molecular axis, while a transition essentially within the carbazole group provides a negative beta (zxx) contribution to beta (EFISH). Therefore, these molecules can only be described with a two-dimensional model as opposed to the 'classical' one-dimensional model for NLO chromophores. Experimental verification of this hypothesis was provided by a combination of two experimental methods, EFISH and hyper Rayleigh scattering (HRS). Each technique probes a different combination of the beta tensor elements, so we could deduce the two contributions. (C) 2000 Elsevier Science S.A. All rights reserved.

The second order nonlinearity of conjugated organic molecules involving, 1,3 indandione derivatives as an acceptor moiety has been studied. Varying the donor from dialkylamino to the chemically similar substituent, N- carbazolyl resulted in a drastic reduction of electric field induced second harmonic (beta) values. For some molecules, even a small negative value of (beta) was received. Quantum chemical calculations indicate that the decrease occurs as a result of two overlapping transitions, which contribute to (beta) with opposite signs. The charge transfer band gives a positive (beta) zzz along the molecular long axis, while a transition essentially within the carbazole moiety provides a negative (beta zzz contribution to (beta EFISH. Thus, these molecules must be described with a 2D model as opposed to the 'classical' model of 1D nonlinear optical chromophores. The prediction of the 2D model was verified experimentally by using a combination of two methods, EFISH and Hyper-Rayleigh Scattering, which probe different combination of the (beta) tensor elements.