Dinuclear silver(I) complexes for the design of metal-ligand networks based on triazolopyrimidines

Silver(I) coordination complexes with the versatile and biomimetic ligands 1,2,4-triazolo[1,5-a]pyrimidine (tp), 5,7-dimethyl-1,2,4-triazolo[1,5-a]pyrimidine (dmtp) and 7-amine-1,2,4-triazolo[1,5-a]pyrimidine (7atp) all feature dinuclear [Ag(2)(μ-tp)(2)](2+) building units (where tp is a triazolopyrimidine derivative), which are the preferred motif, independently of the counter-anion used. According to AIM (atoms in molecules) and ELF (electron localization function) analyses, this fact is due to the great stability of these dinuclear species. The complexes structures range from the dinuclear entities [Ag(2)(μ-tp)(2)(CH(3)CN)(4)](BF(4))(2) (1), [Ag(2)(μ-tp)(2)(CH(3)CN)(4)](ClO(4))(2) (2), [Ag(2)(μ-7atp)(2)](ClO(4))(2) (3) and [Ag(2)(μ-dmtp)(2)(CH(3)CN)](PF(6))(ClO(4)) (4) over the 1D polymer chain [Ag(2)(μ-CF(3)SO(3))(2)(μ-dmtp)(2)](n) (5) to the 3D net {[Ag(2)(μ(3)-tp)(2)](PF(6))(2)·～6H(2)O}(n) (6) with NbO topology.     

Analytical applications of some flotation techniques-a review

A review is given of the principles and more recent applications of foam flotation.     

Very efficient, reusable copper catalyst for carbene transfer reactions under biphasic conditions using ionic liquids

[reaction: see text] The complex {[HC(3,5-Me(2)pz)(3)]Cu(NCMe)}BF(4) catalyzes the transfer of the :CHCO(2)Et unit from ethyl diazoacetate to several saturated and unsaturated substrates with very high yields and under biphasic conditions using the ionic liquid [bmim][PF(6)] and hexane as the reaction medium. The catalyst has been tested for several cycles of recovery and reuse without any loss of activity.     

Macrocyclic chiral receptors toward enantioselective recognition of naproxen

[structure: see text] A macrocyclic receptor based on a bischromenylurea and an alpha,alpha'-(o,o'-dialkyl)diphenyl-p-xylylenediamine spacer provides a C(2) chiral cavity to associate carboxylates by H-bonds. The extent of the selectivity obtained for the racemic receptor 2 and enantiomerically pure (S)-naproxen is 7.2:1. Steric repulsions close to the cavity are decisive for the chiral selectivity.     

Planning federal public investment in Mexico using multiobjective decision making

The scope of this article is showing how multicriteria decision making can be anefficient tool to manage public investment planning in complex situations. Forthis aim, we will analyse the problem in all its aspects: building the modelfrom data using econometrical tools, solving the resulting highly complex modelusing modern efficient techniques (multiobjective meta-heuristics) and helpingthe decision maker to introduce his preferences in order to achieve the mostpreferred solution. This holistic approach let us provide an efficient solutionto a complex public investment planning situation, improving the current stateof the country relating not only economical aspects, but also social and humandevelopment aspects. The real situation studied is focused on Mexico, where, inrecent decades, has undergone remarkable improvements in terms of economicgrowth, which has not been matched by significant improvements in several otherbasic aspects of human development, nor by reductions in regional inequalities.This suggests the need to establish policies aimed at improving these aspectsand reducing inequalities. Federal public investment is an important tool inregional policy to promote and improve these aspects; so we introduce amultiobjective programming problem for planning federal public investment inMexico. This model will focus on improving national levels in four maindimensions of human development (economic growth, education, health andhousing), and on reducing regional inequalities for those dimensions.     

Angular spectrum of diffracted wave fields with apochromatic correction

We report on compensation of diffraction-induced angular dispersion of ultrashort pulses up to a second order. A strategy for chromatic correction profits from high dispersion of kinoform-type zone plates. Ultraflat dispersion curves rely on a saddle point that may be tuned at a prescribed wavelength. Validity of our approach may reach the few-cycles regime.     

Role of the Bridge in Photoinduced Electron Transfer in Porphyrin–Fullerene Dyads

The role of π‐conjugated molecular bridges in through‐space and through‐bond electron transfer is studied by comparing two porphyrin–fullerene donor–acceptor (D–A) dyads. One dyad, ZnP–Ph–C₆₀ (ZnP=zinc porphyrin), incorporates a phenyl bridge between D and A and behaves very similarly to analogous dyads studied previously. The second dyad, ZnP–EDOTV–C₆₀, introduces an additional 3,4‐ethylenedioxythienylvinylene (EDOTV) unit into the conjugated bridge, which increases the distance between D and A, but, at the same time, provides increased electronic communication between them. Two essential outcomes that result from the introduction of the EDOTV unit in the bridge are as follows: 1) faster charge recombination, which indicates enhanced electronic coupling between the charge‐separated and ground electronic states; and 2) the disappearance of the intramolecular exciplex, which mediates photoinduced charge separation in the ZnP–Ph–C₆₀ dyad. The latter can be interpreted as a gradual decrease in electronic coupling between locally excited singlet states of D and A when introducing the EDOTV unit into the D–A bridge.