The robust metal-organic framework compound {[Zn(2)(L)] x 4H(2)O}(infinity) I has been synthesized by hydrothermal reaction of ZnCl(2) and 4,4'-bipyridine-2,6,2',6'-tetracarboxylic acid (H(4)L). Compound I crystallizes in a chiral space group, P4(2)2(1)2, with the chirality generated by the helical chains of hydrogen-bonded guest water molecules rather than by the coordination framework. Removal of guest water molecules from the crystal affords the porous material, [Zn(2)(L)](infinity) (II), which has very high thermal stability and is chemically inert. The N(2) isotherm of II at 77 K suggests a uniform porous structure with a BET surface area of 312.7 m(2)/g and a remarkably strong interaction with N(2) molecules (betaE(0) = 29.6 kJ mol(-)(1)). II also exhibits significant gas storage capacities of 1.08 wt % for H(2) at 4 bar and 77 K and 3.14 wt % (44.0 cm(3)/g, 67 v/v) for methane at 9 Bar at 298 K. The adsorption behavior of II toward organic solvent vapors has also been studied, and isotherms reveal that for different solvent vapors adsorption is dominated by two types of processes, absorbate-absorbate or absorbate-absorbent interactions. The adsorption and desorption kinetic processes in II are determined mainly by the molecular size of the guest species and their interaction with the host.

Highlights: ► Twelve entropy indices were systematically compared in monitoring depth of anesthesia and detecting burst suppression.► Renyi permutation entropy performed best in tracking EEG changes associated with different anesthesia states.► Approximate Entropy and Sample Entropy performed best in detecting burst suppression.Objective: Entropy algorithms have been widely used in analyzing EEG signals during anesthesia. However, a systematic comparison of these entropy algorithms in assessing anesthesia drugs' effect is lacking. In this study, we compare the capability of 12 entropy indices for monitoring depth of anesthesia (DoA) and detecting the burst suppression pattern (BSP), in anesthesia induced by GABAergic agents.Methods: Twelve indices were investigated, namely Response Entropy (RE) and State entropy (SE), three wavelet entropy (WE) measures [Shannon WE (SWE), Tsallis WE (TWE), and Renyi WE (RWE)], Hilbert-Huang spectral entropy (HHSE), approximate entropy (ApEn), sample entropy (SampEn), Fuzzy entropy, and three permutation entropy (PE) measures [Shannon PE (SPE), Tsallis PE (TPE) and Renyi PE (RPE)]. Two EEG data sets from sevoflurane-induced and isoflurane-induced anesthesia respectively were selected to assess the capability of each entropy index in DoA monitoring and BSP detection. To validate the effectiveness of these entropy algorithms, pharmacokinetic/pharmacodynamic (PK/PD) modeling and prediction probability (Pk) analysis were applied. The multifractal detrended fluctuation analysis (MDFA) as a non-entropy measure was compared.Results: All the entropy and MDFA indices could track the changes in EEG pattern during different anesthesia states. Three PE measures outperformed the other entropy indices, with less baseline variability, higher coefficient of determination (R2) and prediction probability, and RPE performed best; ApEn and SampEn discriminated BSP best. Additionally, these entropy measures showed an advantage in computation efficiency compared with MDFA.Conclusion: Each entropy index has its advantages and disadvantages in estimating DoA. Overall, it is suggested that the RPE index was a superior measure. Investigating the advantages and disadvantages of these entropy indices could help improve current clinical indices for monitoring DoA.

The photochemistry of Fe(CO)5 (5) has been studied in heptane, supercritical (sc) Ar, scXe, and scCH4 using time-resolved infrared spectroscopy (TRIR). 3Fe(CO)4 ((3)4) and Fe(CO)3(solvent) (3) are formed as primary photoproducts within the first few picoseconds. Complex 3 is formed via a single-photon process. In heptane, scCH4, and scXe, (3)4 decays to form (1)4 x L (L = heptane, CH4, or Xe) as well as reacting with 5 to form Fe2(CO)9. In heptane, 3 reacts with CO to form (1)4 x L. The conversion of (3)4 to (1)4 x L has been monitored directly for the first time (L = heptane, kobs = 7.8(+/- 0.3) x 10(7) s(-1); scCH4, 5(+/- 1) x 10(6) s(-1); scXe, 2.1(+/- 0.1) x 10(7) s(-1)). In scAr, (3)4 and 3 react with CO to form 5 and (3)4, respectively. We have determined the rate constant (kCO = 1.2 x 10(7) dm3 mol(-1) s(-1)) for the reaction of (3)4 with CO in scAr, and this is very similar to the value obtained previously in the gas phase. Doping the scAr with either Xe or CH4 resulted in (3)4 reacting with Xe or CH4 to form (1)4 x Xe or (1)4 x CH4. The relative yield, [(3)4]:[3] decreases in the order heptane > scXe > scCH4 >> scAr, and pressure-dependent measurements in scAr and scCH4 indicate an influence of the solvent density on this ratio.

A cascade radical cyclization of 2-isocyanoaryl thioethers with H-phosphorus oxides, organoboronic acids, or alkyl radical precursors has been efficiently developed, providing a novel and highly efficient methodology to structurally diverse C2-substituted benzothiazole derivatives with broad functional group tolerance and good yields. This cascade radical process achieves the first cycloaddition of an imidoyl radical from isocyanide to sulfur atom, rending C(sp)-S bond formation.

Time-resolved infrared (TRIR) spectroscopy, a combination of UV flash photolysis and fast infrared detection, is a powerful technique for probing excited states and detecting reaction intermediates. In this Perspective we highlight the application of TRIR to excited states by probing the nature of the lowest excited states of fac-[Re(CO) 3 (dppz-Cl 2 )(R)] n؉ (R ‫؍‬ Cl ؊ (n ‫؍‬ 0), py (n ‫؍‬ 1) and 4-Me 2 N-py (n ‫؍‬ 1); dppz-Cl 2 ‫؍‬ 11,12-dichlorodipyrido-[3,2-a:2Ј,3Ј-c]phenazine) in CH 3 CN. The characterisation of [Cr( 6 -C 6 H 6 )(CO) 2 Xe] and [Re( 5 -C 5 H 5 )(CO) 2 (C 2 H 6 )] in supercritical Xe and liquid ethane solution exemplifies how this technique can be applied to detect new organometallic species.

Employing fast time-resolved infrared (TRIR) spectroscopy we have characterized CpRe(CO)2(n-heptane), CpRe(CO)2(Xe), and CpRe(CO)2(Kr) (Cp = η5-C5H5) at or above room temperature in n-heptane, supercritical Xe, and Kr solution. The reactivity of CpRe(CO)2(n-heptane) with CO (k 2 = 2.1 (±0.5) × 103 mol-1 dm3 s-1) shows this complex to be the least reactive of the reported organometallic alkane complexes. We report a trend in reactivity of the early transition metal alkane complexes. CpRe(CO)2(Xe) and CpRe(CO)2(Kr) are also shown to have significant stability. CpRe(CO)2(Xe) is less reactive toward CO than all of the reported alkane complexes except CpRe(CO)2(n-heptane).

The nucleotide 5 -dGMP and polynucleotide poly(dGdC)⅐poly(dGdC) have been irradiated by using a 200-fs, 200-nm laser pulses and spectrally characterized by using time-resolved infrared spectroscopy. Under the experimental conditions, 200-nm excitation generates both electronic excited states and radical cations through photoionization; the former decay rapidly to vibrationally hot ground state. By using infrared signatures we have been able to follow these processes, and at time scales of >1 ns we observe an infrared marker band at 1,702 cm ؊1 within both 5 -dGMP and the polynucleotide assigned to a photoionized product of guanine. This transient has also been reproduced through indirect chemistry through the reaction with photogenerated carbonate radical with 5 -dGMP. The ability to use time-resolved infrared spectroscopy in this way paves the way for developing solution-phase studies to investigate both direct and indirect radiation chemistry of DNA.DNA damage ͉ electron transfer ͉ guanine radical cation O f the large number of ionizing events per day that are known to be a potential threat to the living cell through DNA damage, only a few are believed to lead to irreparable damage (1). This small number of irreversible events is significant because it is the fundamental step that ultimately leads to mutation and the onset of cancer (2). Oxidative stress is known to be a primary cause of such damage occurring through the formation of radical ions of nucleic acid bases, and the ease with which each individual base is ionized to produce the corresponding base radical cation is determined by its ionization potential, the order being G Ͻ A Ͻ C Ϸ T (3). Thus, within a randomly photoionized DNA strand through hole transfer from one base to the next, damage tends to favor formation of the G base radical (4-6). There is considerable research effort in trying to understand the precise mechanism of long-range electron transfer as a function of the sequence-dependent structure and how this mechanism relates to DNA damage (7-11). UV radiation to initiate DNA base ionization has proven extremely useful for studying direct DNA damage (4-6, 12) along with pulse radiolysis (13). Traditionally, reactions in DNA are monitored by either following the kinetics on the nanosecond time scale using UV͞visible absorption spectroscopy (5, 6, 12, 13) or determining the resulting base damage (single-or double-strand breaks) using hot piperidine treatment or excision enzyme analysis followed by gel electrophoresis (14, 15). Conversely, ESR spectroscopy has provided structural information on ionization products. These studies used either UV͞visible irradiation or pulse radiolysis to produce ionized DNA species in frozen glass at cryogenic temperatures (16)(17)(18)(19) and in solution (20). However, this method did not permit ultrafast time scales to be studied. It is known that the chemical processes involved in DNA damage stretch across a wide range of time domains from femtoseconds to seconds, and being able to observe the earliest event...

The ground and excited state photophysical properties of a series of fac-[Re(L)(CO)(α-diimine)] complexes, where L = Br, Cl, 4-dimethylaminopyridine (dmap) and pyridine (py) have been extensively studied utilizing numerous electronic and vibrational spectroscopic techniques in conjunction with a suite of quantum chemical methods. The α-diimine ligand consists of 1,10-phenanthroline with the highly electron donating triphenylamine (TPA) appended in the 5 position. This gives rise to intraligand charge transfer (ILCT) states lying lower in energy than the conventional metal-to-ligand charge transfer (MLCT) state, the energies of which are red and blue-shifted, respectively, as the ancillary ligand, L becomes more electron withdrawing. The emitting state is ILCT in nature for all complexes studied, characterized through transient absorption and emission, transient resonance Raman (TR), time-resolved infrared (TRIR) spectroscopy and TDDFT calculations. Systematic modulation of the ancillary ligand causes unanticipated variation in the ILCT lifetime by 2 orders of magnitude, ranging from 6.0 μs for L = Br to 27 ns for L = py, without altering the nature of the excited state formed or the relative order of the other CT states present. Temperature dependent lifetime measurements and quantum chemical calculations provide no clear indication of close lying deactivating states, MO switching, contributions from a halide-to-ligand charge transfer (XLCT) state or dramatic changes in spin-orbit coupling. It appears that the influence of the ancillary ligand on the excited state lifetime could be explained in terms of energy gap law, in which there is a correlation between ln( k) and E with a slope of -21.4 eV for the ILCT emission.