Syntheses, structures, and stabilities of aliphatic and aromatic fluorous iodine(I) and iodine(III) compounds::the role of iodine Lewis basicity

The title molecules are sought in connection with various synthetic applications. The aliphatic fluorous alcohols RfnCH2OH (Rfn = CF3(CF2)n–1; n = 11, 13, 15) are converted to the triflates RfnCH2OTf (Tf2O, pyridine; 22–61%) and then to RfnCH2I (NaI, acetone; 58–69%). Subsequent reactions with NaOCl/HCl give iodine(III) dichlorides RfnCH2ICl2 (n = 11, 13; 33–81%), which slowly evolve Cl2. The ethereal fluorous alcohols CF3CF2CF2O(CF(CF3)CF2O)xCF(CF3)CH2OH (x = 2–5) are similarly converted to triflates and then to iodides, but efforts to generate the corresponding dichlorides fail. Substrates lacking a methylene group, RfnI, are also inert, but additions of TMSCl to bis(trifluoroacetates) RfnI(OCOCF3)2 appear to generate RfnICl2, which rapidly evolve Cl2. The aromatic fluorous iodides 1,3-Rf6C6H4I, 1,4-Rf6C6H4I, and 1,3-Rf10C6H4I are prepared from the corresponding diiodides, copper, and RfnI (110–130 °C, 50–60%), and afford quite stable RfnC6H4ICl2 species upon reaction with NaOCl/HCl (80–89%). Iodinations of 1,3-(Rf6)2C6H4 and 1,3-(Rf8CH2CH2)2C6H4 (NIS or I2/H5IO6) give 1,3,5-(Rf6)2C6H3I and 1,2,4-(Rf8CH2CH2)2C6H3I (77–93%). The former, the crystal structure of which is determined, reacts with Cl2 to give a 75:25 ArICl2/ArI mixture, but partial Cl2 evolution occurs upon work-up. The latter gives the easily isolated dichloride 1,2,4-(Rf8CH2CH2)2C6H3ICl2 (89%). The relative thermodynamic ease of dichlorination of these and other iodine(I) compounds is probed by DFT calculations

Biological Earth observation with animal sensors.

Space-based tracking technology using low-cost miniature tags is now delivering data on fine-scale animal movement at near-global scale. Linked with remotely sensed environmental data, this offers a biological lens on habitat integrity and connectivity for conservation and human health; a global network of animal sentinels of environmen-tal change

Circadian pacemaker coupling by multi-peptidergic neurons in the cockroach Leucophaea maderae

Lesion and transplantation studies in the cockroach, Leucophaea maderae, have located its bilaterally symmetric circadian pacemakers necessary for driving circadian locomotor activity rhythms to the accessory medulla of the optic lobes. The accessory medulla comprises a network of peptidergic neurons, including pigment-dispersing factor (PDF)-expressing presumptive circadian pacemaker cells. At least three of the PDF-expressing neurons directly connect the two accessory medullae, apparently as a circadian coupling pathway. Here, the PDF-expressing circadian coupling pathways were examined for peptide colocalization by tracer experiments and double-label immunohistochemistry with antisera against PDF, FMRFamide, and Asn13-orcokinin. A fourth group of contralaterally projecting medulla neurons was identified, additional to the three known groups. Group one of the contralaterally projecting medulla neurons contained up to four PDF-expressing cells. Of these, three medium-sized PDF-immunoreactive neurons coexpressed FMRFamide and Asn13-orcokinin immunoreactivity. However, the contralaterally projecting largest PDF neuron showed no further peptide colocalization, as was also the case for the other large PDF-expressing medulla cells, allowing the easy identification of this cell group. Although two-thirds of all PDF-expressing medulla neurons coexpressed FMRFamide and orcokinin immunoreactivity in their somata, colocalization of PDF and FMRFamide immunoreactivity was observed in only a few termination sites. Colocalization of PDF and orcokinin immunoreactivity was never observed in any of the terminals or optic commissures. We suggest that circadian pacemaker cells employ axonal peptide sorting to phase-control physiological processes at specific times of the day

Partially Shielded Fe(CO)₃ Rotors: Syntheses, Structures, and Dynamic Properties of Complexes with Doubly <i>trans</i> Spanning Diphosphines, <i>trans</i>-Fe(CO)₃(PhP((CH₂)_<i>n</i>)₂PPh)

Reactions of Fe­(CO)₃(η⁴-benzylideneacetone) and PhP­((CH₂)_<i>m</i>CHCH₂)₂ (<i>m</i> = <b>a</b>, 4; <b>b</b>, 5; <b>c</b>, 6) give <i>trans</i>-Fe­(CO)₃(PhP­((CH₂)_<i>m</i>CHCH₂)₂)₂ (<b>2a</b>–<b>c</b>, 28–70%), which are treated with Grubbs’ catalyst (15 mol %; refluxing CH₂Cl₂). NMR analyses of the crude <i>inter</i>ligand metathesis products <i>trans</i>-Fe­(CO)₃(PhP­((CH₂)_<i>m</i>CHCH­(CH₂)_<i>m</i>)₂PPh) (<b>3a</b>–<b>c</b>, 30–31%) suggest <i>Z</i>/<i>E</i> CC mixtures and/or byproducts from <i>intra</i>ligand metathesis or oligomers. Subsequent hydrogenations (5 bar/cat. Rh­(Cl)­(PPh₃)₃ or PtO₂) afford <i>trans</i>-Fe­(CO)₃(PhP­((CH₂)_<i>n</i>)₂PPh) (<b>4a</b>–<b>c</b>, 69–77%; <i>n</i> = 2<i>m</i> + 2, <i>synperiplanar</i> phenyl groups), which density functional theory calculations show to be more stable than isomers derived from other metathesis modes. Crystallizations give (<i>E</i>,<i>E</i>)-<b>3a</b> and <b>4b</b>, the X-ray structures of which are determined and analyzed. Variable-temperature ¹³C­{¹H} NMR experiments show that rotation of the Fe­(CO)₃ moiety in <b>4b</b> is rapid on the NMR time scale (RT to 0 °C; Δ<i>G</i>^⧧_273 K ≤ 12.8 kcal/mol), but that in <b>4a</b> is not (RT to 105 °C; Δ<i>G</i>^⧧_378 K ≥ 17.9 kcal/mol). These data indicate rotational barriers lower than those in analogues in which three methylene chains connect the phosphorus atoms, <i>trans</i>-Fe­(CO)₃(P­((CH₂)_<i>n</i>)₃P)

Ruthenium(ii) arene complexes with chelating chloroquine analogue ligands: Synthesis, characterization and in vitro antimalarial activity.

Three new ruthenium complexes with bidentate chloroquine analogue ligands, [Ru(η(6)-cym)(L(1))Cl]Cl (1, cym = p-cymene, L(1) = N-(2-((pyridin-2-yl)methylamino)ethyl)-7-chloroquinolin-4-amine), [Ru(η(6)-cym)(L(2))Cl]Cl (2, L(2) = N-(2-((1-methyl-1H-imidazol-2-yl)methylamino)ethyl)-7-chloroquinolin-4-amine) and [Ru(η(6)-cym)(L(3))Cl] (3, L(3) = N-(2-((2-hydroxyphenyl)methylimino)ethyl)-7-chloroquinolin-4-amine) have been synthesized and characterized. In addition, the X-ray crystal structure of 2 is reported. The antimalarial activity of complexes 1-3 and ligands L(1), L(2) and L(3), as well as the compound N-(2-(bis((pyridin-2-yl)methyl)amino)ethyl)-7-chloroquinolin-4-amine (L(4)), against chloroquine sensitive and chloroquine resistant Plasmodium falciparum malaria strains was evaluated. While 1 and 2 are less active than the corresponding ligands, 3 exhibits high antimalarial activity. The chloroquine analogue L(2) also shows good activity against both the chloroquine sensitive and the chloroquine resistant strains. Heme aggregation inhibition activity (HAIA) at an aqueous buffer/n-octanol interface (HAIR(50)) and lipophilicity (D, as measured by water/n-octanol distribution coefficients) have been measured for all ligands and metal complexes. A direct correlation between the D and HAIR(50) properties cannot be made because of the relative structural diversity of the complexes, but it may be noted that these properties are enhanced upon complexation of the inactive ligand L(3) to ruthenium, to give a metal complex (3) with promising antimalarial activity

Legislative Documents

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Three-Fold Intramolecular Ring Closing Alkene Metatheses of Square Planar Complexes with <i>cis</i> Phosphorus Donor Ligands P(X(CH₂)_<i>m</i>CHCH₂)₃ (X = −, <i>m</i> = 5–10; X = O, <i>m</i> = 3–5): Syntheses, Structures, and Thermal Properties of Macrocyclic Dibridgehead Diphosphorus Complexes

Reactions of <i>cis</i>-PtCl₂(P­((CH₂)_<i>m</i>CHCH₂)₃)₂ and Grubbs’ first generation catalyst and then hydrogenations afford <i>cis</i>-PtCl₂(P­((CH₂)_<i>n</i>)₃P) (<i>cis</i>-<b>2</b>; <i>n</i> = 2<i>m</i> + 2 = 12 (<b>b</b>), 14 (<b>c</b>), 16 (<b>d</b>), 18 (<b>e</b>), 20 (<b>f</b>), 22 (<b>g</b>); 6–40%), derived from 3-fold <i>interligand</i> metatheses. The phosphite complexes <i>cis</i>-PtCl₂(P­(O­(CH₂)_<i>m</i>*CHCH₂)₃)₂ are similarly converted to <i>cis</i>-PtCl₂(P­(O­(CH₂)_<i>n</i>*O)₃P) (<i>cis</i>-<b>5</b>; <i>n*</i> = 8 (<b>a</b>), 10 (<b>b</b>), 12 (<b>c</b>), 10–20%). The substitution products <i>cis</i>-PtPh₂(P­((CH₂)_<i>n</i>)₃P) (<i>cis</i>-<b>6c</b>,<b>d</b>) and <i>cis</i>-PtI₂(P­(O­(CH₂)₁₀O)₃P) are prepared using Ph₂Zn and NaI, respectively. Crystal structures of <i>cis</i>-<b>2c</b>,<b>d</b>,<b>f</b>, <i>cis</i>-<b>5a</b>,<b>b</b>, and <i>cis</i>-<b>6c</b> show one methylene bridge that roughly lies in the platinum coordination plane and two that are perpendicular. The thermal behavior of the complexes is examined. When the bridges are sufficiently long, they rapidly exchange via an unusual “triple jump rope” motion over the PtX₂ moieties. NMR data establish Δ<i>H</i>^⧧, Δ<i>S</i>^⧧, and Δ<i>G</i>_298K^⧧/Δ<i>G</i>_393K^⧧ values of 7.8 kcal/mol, −27.9 eu, and 16.1/18.8 kcal/mol for <i>cis</i>-<b>2d</b>, and a Δ<i>G</i>_393K^⧧ of ≥19.6 kcal/mol for the shorter bridged <i>cis</i>-<b>2c</b>. While <i>cis</i>-<b>2c</b>,<b>g</b> gradually convert to <i>trans</i>-<b>2c</b>,<b>g</b> at 150–185 °C in haloarenes, <i>trans</i>-<b>2c</b>,<b>g</b> give little reaction under analogous conditions, establishing the stability order <i>trans</i> > <i>cis</i>. Similar metathesis/hydrogenation sequences with octahedral complexes containing two <i>cis</i> phosphine ligands, <i>fac</i>-ReX­(CO)₃(P­((CH₂)₆CHCH₂)₃)₂ (X = Cl, Br), give <i>fac</i>-ReX­(CO)₃(P­(CH₂)₁₃CH₂)­((CH₂)₁₄)­(P­(CH₂)₁₃CH₂) (19–50%), which are derived from a combination of <i>interligand</i> and <i>intraligand</i> metathesis. The relative stabilities of <i>cis</i>/<i>trans</i> and other types of isomers are probed by combinations of molecular dynamics and DFT calculations

Three-Fold Intramolecular Ring Closing Alkene Metatheses of Square Planar Complexes with <i>cis</i> Phosphorus Donor Ligands P(X(CH₂)_<i>m</i>CHCH₂)₃ (X = −, <i>m</i> = 5–10; X = O, <i>m</i> = 3–5): Syntheses, Structures, and Thermal Properties of Macrocyclic Dibridgehead Diphosphorus Complexes

Reactions of <i>cis</i>-PtCl₂(P­((CH₂)_<i>m</i>CHCH₂)₃)₂ and Grubbs’ first generation catalyst and then hydrogenations afford <i>cis</i>-PtCl₂(P­((CH₂)_<i>n</i>)₃P) (<i>cis</i>-<b>2</b>; <i>n</i> = 2<i>m</i> + 2 = 12 (<b>b</b>), 14 (<b>c</b>), 16 (<b>d</b>), 18 (<b>e</b>), 20 (<b>f</b>), 22 (<b>g</b>); 6–40%), derived from 3-fold <i>interligand</i> metatheses. The phosphite complexes <i>cis</i>-PtCl₂(P­(O­(CH₂)_<i>m</i>*CHCH₂)₃)₂ are similarly converted to <i>cis</i>-PtCl₂(P­(O­(CH₂)_<i>n</i>*O)₃P) (<i>cis</i>-<b>5</b>; <i>n*</i> = 8 (<b>a</b>), 10 (<b>b</b>), 12 (<b>c</b>), 10–20%). The substitution products <i>cis</i>-PtPh₂(P­((CH₂)_<i>n</i>)₃P) (<i>cis</i>-<b>6c</b>,<b>d</b>) and <i>cis</i>-PtI₂(P­(O­(CH₂)₁₀O)₃P) are prepared using Ph₂Zn and NaI, respectively. Crystal structures of <i>cis</i>-<b>2c</b>,<b>d</b>,<b>f</b>, <i>cis</i>-<b>5a</b>,<b>b</b>, and <i>cis</i>-<b>6c</b> show one methylene bridge that roughly lies in the platinum coordination plane and two that are perpendicular. The thermal behavior of the complexes is examined. When the bridges are sufficiently long, they rapidly exchange via an unusual “triple jump rope” motion over the PtX₂ moieties. NMR data establish Δ<i>H</i>^⧧, Δ<i>S</i>^⧧, and Δ<i>G</i>_298K^⧧/Δ<i>G</i>_393K^⧧ values of 7.8 kcal/mol, −27.9 eu, and 16.1/18.8 kcal/mol for <i>cis</i>-<b>2d</b>, and a Δ<i>G</i>_393K^⧧ of ≥19.6 kcal/mol for the shorter bridged <i>cis</i>-<b>2c</b>. While <i>cis</i>-<b>2c</b>,<b>g</b> gradually convert to <i>trans</i>-<b>2c</b>,<b>g</b> at 150–185 °C in haloarenes, <i>trans</i>-<b>2c</b>,<b>g</b> give little reaction under analogous conditions, establishing the stability order <i>trans</i> > <i>cis</i>. Similar metathesis/hydrogenation sequences with octahedral complexes containing two <i>cis</i> phosphine ligands, <i>fac</i>-ReX­(CO)₃(P­((CH₂)₆CHCH₂)₃)₂ (X = Cl, Br), give <i>fac</i>-ReX­(CO)₃(P­(CH₂)₁₃CH₂)­((CH₂)₁₄)­(P­(CH₂)₁₃CH₂) (19–50%), which are derived from a combination of <i>interligand</i> and <i>intraligand</i> metathesis. The relative stabilities of <i>cis</i>/<i>trans</i> and other types of isomers are probed by combinations of molecular dynamics and DFT calculations