As the installation of solar-photovoltaic and wind-generation systems continue to grow, the location must be strategically selected to maintain a reliable grid. However, such strategies are commonly ...subject to system adequacy constraints, while system security constraints (e.g., frequency stability, voltage limits) are vaguely explored. This may lead to inaccuracies in the optimal placement of the renewables, and thus maximum benefits may not be achieved. In this context, this paper proposes an optimization-based mathematical framework to design a robust distributed generation system, able to keep system stability in a desired range under system perturbance. The optimum placement of wind and solar renewable energies that minimizes the impact on system stability in terms of the standard frequency deviation is obtained through particle swarm optimization, which is developed in Python and executed in PowerFactory-DIgSILENT. The results reveal that the proposed approach has the potential to reduce the influence of disturbances, enhancing critical clearance time before frequency collapse and supporting secure power system operation.
Two series of dinuclear organotin macroheterocycles of general formula R
2
Sn{
Ch
(C
6
H
4
CH
2
)
2
}
2
SnR
2
Ch
= O with R =
n
-Bu (
2a
), Bn (
3a
), Ph (
4a
) and
Ch
= S with R =
n
-Bu (
2b
...), Bn (
3b
), Ph (
4b
) were easily synthetized by a Barbier-type reaction assisted by sonochemical activation of metallic magnesium. The
119
Sn{
1
H} NMR data for all compounds and the X-ray single-crystal diffraction studies for
2a
and
4a
confirmed the presence of a central Sn atom in a four-coordinate environment. The molecular structures of
2a
and
4a
showed puckered 16-membered macroheterocycles. The tin and oxygen atoms are in the interior of the cavity of the macrocycle, surrounded by hydrophobic C–H bonds. A Hirshfeld surface analyses of
2a
and
4a
showed that the macrocycles are linked by weak C–H···π, C···C, and H···H non-covalent interactions. The pairwise interaction energies showed that the cohesion between the macrocycles are mainly due to dispersion forces.
Cu(I)(SacNacDipp)(PPh3) as redox mediator for glucose determination biosensor using the enzyme glucose oxidase.
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•Two new β-thioketoiminate–copper and –palladium complexes were ...synthetized.•The molecular structures of both compounds were determined.•The Cu(SacNacDipp)(PPh3) has electrocatalytic activity detecting hydrogen peroxide.•A glucose biochemical sensor of copper(I) was generated.
The synthesis of the Cu(SacNacDipp)(PPh3) (1) and Pd(SacNacDipp)Cl(PPh3) (2) complexes was achieved from deprotonation of the 4-(2,6-diisopropylphenylamino)-3-penten-2-thione ligand. Both compounds were characterized in solution by IR and NMR studies and their molecular structures were determined by single crystal X-ray diffraction studies. The electrochemical properties of both complexes were studied to evaluate their capability to detect hydrogen peroxide; as a result of its electrochemical behavior, 1 was used as redox mediator for glucose determination biosensor using the enzyme glucose oxidase (GOx).
This report illustrates a successful C–H···Hal synthon-directed strategy to promote supramolecular aggregation of molecular luminescent complexes 1–6 into two- or three-dimensional supramolecular ...architectures. The tin complexes were prepared from the reaction of R n SnHal4–n compounds (R = n-Bu, Ph; Hal = Cl, Br; n = 0, 1) with (C5H4N)HCN(C6H4)EH Schiff bases by either step-by-step synthesis E = O (PyNO) or multicomponent reaction E = S (PyNS). Compounds 1–6 were characterized by IR, Raman, and 1H, 13C, and 119Sn NMR spectroscopic studies as well as by X-ray diffraction studies. In addition, the fluorescent properties of all compounds were also investigated in the solid state and in THF solutions; the emission wavelengths ranged from orange to red (λmax = 591–626 nm). Detailed structural characterization of the supramolecular organization of ordered solids revealed overall 2D and 3D interlinked networks driven by extensive C–H···Hal–Sn (Hal = Cl, Br) weak hydrogen bonds as primordial synthon and further stabilized by π···π stacking interactions as well as C–H···π, C–H···O, or C–H···N contacts. Hirshfeld surface analysis and DFT calculations were used to asses additional insights into crystal structural features.
This report illustrates a successful mercury-directed self-assembly strategy via the design and synthesis of a new bifunctional bis-dithiocarbamate ligand K2L. This ligand efficiently self-assembles ...with Hg(II) to afford a novel bimetallic 28-membered macrocycle, Hg2L2. This supramolecular complex persists as a discrete macrocyclic structure in solution as evidenced by two-dimensional DOSY NMR. The X-ray diffraction analysis confirms the formation of the bimetallic metallomacrocycle where both bis-dithiocarbamate units are asymmetrically bound to the mercury centers. Analysis of noncovalent interactions in the crystalline state reveals very close Hg···Hg intramolecular mercurophilic contacts (≈ 3.3 Å) and the action of C–H···π (chelate) interactions.
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•Ten NHC-Ag and Au derivatives were synthesized by using an effective methodology.•The seven single-crystal structures showed interesting structural features.•Antibacterial activity ...of NHC compounds was determined via the Kirby–Bauer method.•Compounds shown good in vitro activity against Gram positive and negative strains.
Synthetic, structural, and antibacterial studies of a series of functionalized monocarbene NHC of silver(I) and gold(I) complexes are reported. Silver NHC compounds of general formula AgCl{NHC} 1a–e have been obtained in excellent yields by the traditional synthetic method using Ag2O, as starting material, and the corresponding 3-substituted 1-(2-methylallyl)imidazolium chloride salts L1–L5. NHC–Ag(I) compounds 1a–e were used as transmetalation agents to synthesize monocarbenes NHC–Au(I) complexes AuCl{NHC} 2a–e in good yields by using AuCl(SMe2) as a source of gold (I). All compounds were characterized by spectroscopic and analytic techniques. The molecular structures of seven compounds L3, 1a, 1d, 2a, 2a′, 2c and 2d were confirmed by a single-crystal X-ray diffraction method. Elemental analysis and powder X-ray diffraction (PXRD) experimental studies were also carried out. In addition, in vitro antibacterial assays, of the series NHC–Ag(I) 1a–e and NHC–Au(I) 2a–e were tested against three Gram positives: Staphylococcus aureus, Bacillus subtilis, and Enterococcus faecalis, and three Gram negatives: Pseudomonas aeruginosa, Escherichia coli and Salmonella typhi bacterial strains by Kirby–Bauer’s disk diffusion method. Silver compounds 1a, 1d, and all gold compounds showed excellent activity against S. aureus and S. typhi, though both types of complexes showed antibacterial activity, gold complexes were found to be the most active antibacterials. Good activity was shown by complexes 1a and 1d against P. aerouginosa, E. coli, S. typhi, S. aureus and E. feacalis and compounds 2b and 2e against E. faecalis. An excellent activity was shown by compound 2a against S. aureus with the highest inhibitory zone of 26 ± 0 mm.
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•1,1-dithioligands with diphenyltin dihalides yielded heteroleptic tin(IV) complexes.•The four pairs of tin complexes displayed pentacoordination at the Sn central atom.•Formation of ...CH---X, S---H, S---S, and pi---H non-covalent interactions is enhanced.
The reaction of enantiomerically pure (+) and (−) menthol as well as (R)-(+)- and (S)-(−)N-benzyl-1-phenylethylamine with carbon disulfide in presence of potassium hydroxide yielded, respectively, chiral xanthate and dithiocarbamates as their potassium salts. These chiral 1,1-dithioligands were reacted with diphenyltin dihalides to produce four enantiomeric and isostructural pairs of diorganotin complexes of formula (+)-SnPh2{xanMEN}Cl (1), (−)-SnPh2{xanMEN}Cl (1m), (+)-SnPh2{xanMEN}Br (2), (−)-SnPh2{xanMEN}Br (2m), (+)-SnPh2{dtcBPE}Cl (3), (−)-SnPh2{dtcBPE}Cl (3m), (+)-SnPh2{dtcBPE}Br (4), and (−)-SnPh2{dtcBPE}Br (4m). The 119Sn{1H} NMR data and the X-ray single-crystal diffraction studies of the eight heteroleptic compounds confirmed the anisobidentate pattern of the {(RnECS2}− (E = O, n = 1; E = N, n = 2) monoanionic ligand. The presence of halides and sulfur atoms enhanced the formation of CH⋯X, S⋯H, S⋯S, and pi⋯H non-covalent interactions in the crystalline state. A Hirshfeld surface analysis was carried out to identify these significant intermolecular contacts in the complexes. The less hindered tin atom in the xanthate complexes displayed a CS⋯X–Sn interaction of attractive nature.
The synthesis of Rh(III)Cp*–NHC and Ir(III)Cp*–NHC complexes from amino acid ligand precursors is reported. These complexes were tested as catalysts in TH with good conversions in 2 h and TON values ...greater than 100.
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Heteroleptic RhIIICp*(NHC) and IrIIICp*(NHC) complexes bearing a N-amino acid functionality derived from imidazolium salts were synthesized and characterized by NMR, IR, HR-MS, and single-crystal X-ray diffraction. A discussion of the structure of the RhCp*{κ2(C,O)–NHC}Cl complex 3f as a pair of diastereomers is presented. Catalysts were assessed for the transfer hydrogenation (TH) of ketones in basic propan-2-ol, obtaining good yields for the reduction products. A chromatographic method applied for measurements of compounds in TH as analytes was validated. The Rh and Ir complexes described here offer an original approach in the development of catalysts based in classic NHC precursors.
The 2-(2-pyridyl)benzothiazolines of general formula {C6H4N(H)CS}(C5H4N)R (R = H, 1; R = Me, 2; R = Ph, 3 and, R = C5H4N-2, 4) in presence of Pd(tmeda)Me2 or Pd(μ-Cl)(η3-C3H5)2 are precursors of ...N,N,S-tridentate Schiff bases for the formation of organopalladium(II) complexes. From the opening reactions of the thiazoline ring, the mononuclear methylpalladium(II) chlorocomplexes (1a–4a), the dinuclear (η3–allyl)palladium(II) dichloro complexes (1b–3b) and, the trinuclear (η3–allyl)palladium(II) trichloro complex 4c were obtained. Crystals structures of complexes 1a·1/6THF and 3b are stabilized by π---π stacking, CH---π, H---S and CH---Cl. The formation of η3-allylcomplexes 1b–3b and 4c by DFT calculations was also evaluated.
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The synthesis of mononuclear Pd(II) complexes of type Pd(Ln)Me (n = 1–4, 1a–4a) and dinuclear (η3–allyl)palladium(II) dichloro complexes Pd2(Ln)(η3-C3H5)Cl2 (n = 1–3, 1b–3b) derived from 2-R-(2-pyridyl)benzothiazolines used as Schiff bases precursors (R = H, 1; R = Me, 2; R = Ph, 3; R = C5H4N-2, 4) is reported. The formation of the trinuclear complex Pd3(L4)(η3-C3H5)2Cl3 (4c) and its behavior in solution is also described. Complexes 1a–4a, 1b–3b and 4c were obtained from the thiazole ring-opening reaction of precursors 1–4 in presence of the Pd(tmeda)Me2 and Pd(μ -Cl)(η3-C3H5)2 starting materials. The {Ln}− anionic Schiff bases obtained showed a versatile behavior towards coordination to Pd(II) ion; in 1a–4a the ligand acted as tricoordinate whilst in 1b–3b and 4c, {Ln}− acted as mono- and tridentate ligand, respectively.
1a–4a were stable complexes in DMSO‑d6 solution; the dinuclear 1b–3b and trinuclear 4c complexes showed the dissociation of S→Pd bond in DMSO‑d6 solution. Complexes 3a and 3b were characterized by X-ray diffraction studies and a distorted square planar geometry around the central Pd(II) ion was observed in the two five–membered chelate rings. A systematic analysis based on DFT calculation of the structural, electronic, and thermochemistry properties was performed for η3-ally complexes 1b–3b and 4c.
Structural and electronic properties of a series of 25 phosphonate derivatives were analyzed applying density functional theory, with the exchange-correlation functional PBEPBE in combination with ...the 6-311++G** basis set for all atoms. The chemical reactivity of these derivatives has been interpreted using quantum descriptors such as frontier molecular orbitals (HOMO, LUMO), Hirshfeld charges, molecular electrostatic potential, and the dual descriptor
Δ
f
(
r
)
. These descriptors are directly related to experimental median lethal dose (
LD
50
)
, expressed as its decimal logarithm
A
obs
=
log
10
(
LD
50
)
through a multiple linear regression equation. The proposed model predicts the toxicity of phosphonates in function of the volume (
V
), the load of the most electronegative atom of the molecule (
q
), and the eigenvalue of the molecular orbital HOMO (
E
HOMO
)
. The obtained values in the internal validation of the model are:
R
2
=
82.71
%,
R
ADJ
2
=
80.24
%,
F
=
33.5
,
δ
K
=
0.169
,
δ
Q
=
0.011
,
R
P
=
0.423
,
R
N
=
-
0.025
(
-
0.311
)
, and
Q
boot
2
=
75.45
%. The toxicity of nine phosphonate derivatives used as test molecules was adequately predicted by the model. The theoretical results indicate that the oxygen atom of the O=P group plays an important role in the interaction mechanism between the phosphonate and the acetylcholinesterase enzyme, inhibiting the removal of the proton of the ser-200 residue by the his-440 residue.
