How offshore wind could become economically attractive in low-resource regions like Indonesia.

The current focus of offshore wind industry and academia lies on regions with strong winds, neglecting areas with mild resources. Photovoltaics' cost reductions have shown that even mild resources can be harnessed economically, especially where electricity prices are high. Here, we study the technical and economic potential of offshore wind power in Indonesia as an example of mild-resource areas, using bias-corrected ERA5 data, turbine-specific power curves, and a detailed cost model. We show that low-wind-speed turbines could produce up to 6,816 TWh/year, which is 25 times Indonesia's electricity generation in 2018 and 3 times the projected 2050 generation, and up to 166 PWh/year globally. Although not yet competitive against current offshore turbines, low-wind turbines could become a crucial piece of the global climate mitigation effort in regions with vast marine areas and high electricity prices. As low-wind-speed turbines are not yet on the market, we recommend prioritizing their development.

Luminescent gold-thallium derivatives with a pyridine-containing 12-membered aza-thioether macrocycle.

The coordination modes of the ligand 2,5,8-trithia[9](2,6)pyridinophane (L) to thallium(i), gold(iii) and gold(i) have been studied. Thallium(i) is coordinated by the macrocyclic ligand in [Tl(L)](PF6) (1) through all the sulfur and nitrogen atoms, in a distorted square-pyramidal geometry with the thallium(i) ion in the apical position and with the presence of an inert lone pair. Gold(iii) is bonded by the ligand only through the nitrogen of the pyridine group in [AuCl3(L)] (2), whereas two AuI-C6F5 fragments coordinate the sulfur atoms next to the pyridine moiety of the ligand in [{Au(C6F5)}2(µ-L)] (3), which form a linear polymer through intermolecular aurophilic contacts. The heterometallic TlI/AuI complex {[Au(C6F5)2Tl]2(L)}n (4) features a polymeric structural nature with a metallic pseudo-rhombic Au2Tl2 core, which repeats itself forming a zig-zag polymer. In each Au2Tl2 unit only one thallium atom is bonded by the NS3 donor set of the macrocyclic ligand and also forms two unsupported Au-Tl bonds with two [Au(C6F5)2]- units in an overall pseudo-octahedral geometry. The other thallium atom similarly bridges the same [Au(C6F5)2]- units and links a neighbouring Au2Tl2 moiety, thus exhibiting a distorted trigonal planar geometry being bonded only to three gold atoms with unsupported Au-Tl interactions. This complex displays an interesting thermochromic behaviour showing emissions mainly resulting from MM'CT transitions at room temperature. At 77 K a dual emission appears, probably arising from the two different thallium environments. DFT calculations have been carried out in the attempt to investigate the origin of the emissions of complex 4.

Tunable from Blue to Red Emissive Composites and Solids of Silver Diphosphane Systems with Higher Quantum Yields than the Diphosphane Ligands.

PMMA composites and solids of complexes of formulas [AgX(P-P)]n [n = 1 and 2; X = Cl, NO3, ClO4, CF3COO, and OTf; P-P = dppb, xantphos, (PR2)2C2B10H10 (R = Ph and iPr)] display the whole palette of colors from blue to red upon selection of the anionic ligand (X) and the diphosphane (P-P). The diphosphane seems to play the most important role in tuning the emission energy and thermally activated delayed fluorescence (TADF) behavior. The PMMA composites of the complexes exhibit higher quantum yields than that of the diphosphane ligands and those with dppb are between 28 and 53%. Remarkably, instead of blue-green emissions which dominate the luminescence of silver diphosphane complexes in rigid phases, those with carborane diphosphanes are yellow-orange or orange-red emitters. Theoretical studies have been carried out for complexes with P-P = dppb, X = Cl; P-P = dppic, X = NO3; P-P = dppcc, X = Cl, NO3, and OTf and the mononuclear complexes [AgX(xantphos)] (X = Cl, Br). Optimization of the first excited triplet state was only possible for [AgX(xantphos)] (X = Cl and Br). A mixed MLCT and MC nature could be attributed to the S0 → T1 transition in these three-coordinated complexes.

Bioactive and luminescent indole and isatin based gold(i) derivatives.

A series of luminescent monometallic [AuL(PPh3)] (1-3) and bimetallic [Au2(µ-dppe)L2] (4, 6, 8) and [Au2(µ-dppp)L2] (5, 7, 9) complexes, where L is either 4-cyano-indole, isatin, or 5,7-dimethyl-isatin, and dppe and dppp are 1,2-bis(diphenylphosphino)ethane and 1,3-bis(diphenylphosphino)propane, respectively, have been synthesised. X-ray diffraction confirmed the tendency to establish aurophillic interations for those complexes containing dppe. Luminescence studies and theoretical calculations revealed a different origin for both families, i.e. indole and isatin species. Thus, indole derivatives presented a ligand-to-ligand-charge-transfer transition (LLCT) from the indole to the PPh3 fragment, whereas for the isatin derivatives an intraligand-charge-transfer transition (ILCT) within the isatin fragment is proposed. In both cases, the gold centre was slightly implicated as a ligand-to-metal-charge transfer transition (LMCT) (from the indole/isatin to Au(i)). Cell antiproliferative assays in lung cancer cells (A549), leukemia Jurkat-pLVTHM and Jurkat-shBak cells (cisplatin sensitive and resistant, respectively) showed excellent cytotoxic values (10.11-0.28 µM), showing the leukemia cells to be the most sensitive and the bimetallic species to be the most active agents. Preliminary studies associated the cytotoxicity with a combination of different factors, the metallic fragment being mainly responsible. Remarkably, these complexes are able to inhibit the cellular growth of cisplatin resistant Jurkat-shBak cells highlighting their promising future as an alternative anticancer agent.

Synthesis of Gold(III) Complexes with Bidentate Amino-Thiolate Ligands as Precursors of Novel Bifunctional Acyclic Diaminocarbenes.

Two neutral bis(pentafluorophenyl)thiolate gold(III) complexes with the unsymmetrical S^N ligands 2-aminothiophenol or cysteamine have been synthesized and their reactivity has been studied. Homo- and heterodinuclear compounds were obtained by their coordination to gold(I) or silver(I) derivatives through the sulfur atom. Interestingly, a tetranuclear derivative bearing short gold(I)···gold(I) and the more unusual gold(I)···gold(III) interactions has been prepared. These amino-thiolate derivatives can be used as precursors for the synthesis of novel gold(III) acyclic diaminocarbene complexes by reaction with isocyanides CNR. The nucleophilic attack of the amino group to isocyanide molecules affords the synthesis of unprecedented bidentate C^S acyclic diaminocarbene ligands. All of the complexes are air- and moisture-stable at room temperature and have been spectroscopically and structurally characterized.

A stable gold(i)-enyne species obtained by alkyne carboauration in a complex rearrangement.

An unprecedented tetranuclear gold derivative with unusual gold-enyne moieties is prepared by a mild and neat rearrangement of a dinuclear gold complex with a bridging bis(diphenylphosphino)alkyne and terminal alkynyl ligands. The complex originates as a consequence of an intramolecular addition of the AuC[triple bond, length as m-dash]CTol fragment to the internal diphosphine triple bond Ph2PC[triple bond, length as m-dash]CPPh2. The crystal structure of the tetranuclear complex shows a dinuclear metallacycle with a very short AuAu bond interaction and bridging phosphino-enyne ligands. This disposition clearly stabilises the elusive vinyl gold species omnipresent as intermediates in gold-catalysed reactions.

Polynuclear cage-like Au(i) phosphane complexes based on a S2- template: observation of multiple luminescence in coordinated polyaromatic systems.

A rational approach to the synthesis of cage-like compounds has been realized to build a new family of sulfido-phosphane Au(i) polynuclear complexes. Ditopic phosphane ligands with an extended aromatic system were used to obtain cage compounds with a clearly determined geometry. Au(i) complexes have been fully characterised in solution using spectroscopy methods, and DFT optimisation of the molecular structure gives additional arguments in favour of the suggested structural patterns. All complexes obtained are luminescent in solution and in the solid state, and display multiple emissions with an unusual combination of two phosphorescence bands and one fluorescence band. DFT calculations show that multiple emissions were mainly determined by 1IL and metal perturbed 3IL transitions. The ratio of singlet and triplet emission components depends on the distance between the ligand chromophoric centre and Au(i).

Cytotoxicity and biodistribution studies of luminescent Au(i) and Ag(i) N-heterocyclic carbenes. Searching for new biological targets.

A range of fluorescent and biologically compatible gold(i)-N-heterocyclic carbenes bearing acridine as a wingtip group and either a 2-mercaptopyridine or a tetra-O-acetyl-1-thio-ß-d-glucopyranoside as an ancillary ligand has been synthesised. Their luminescence, cytotoxicity and biodistribution have been investigated together with those of analogous gold(i) and silver(i) chloride- and bis-NHC complexes. All complexes displayed emissions based on IL transitions centred on the acridine moiety. The cytotoxic activity measured in lung, A549, and pancreatic, MiaPaca2, carcinoma cell lines revealed a general cytotoxicity pattern (thiolate > biscarbene > chloride derivatives) and flow cytometry assays pointed towards apoptosis as the cell death mechanism. Moreover, fluorescence cell microscopy disclosed an unusual biodistribution behavior, being mainly localised in lysosomes and to a lesser extent in the nucleus. Preliminary DNA interaction experiments suggested the metal fragment and not the acridine moiety as responsible for such biodistribution, which widen the scope for new biological targets.

Bioactive gold(i) complexes with 4-mercaptoproline derivatives.

Unprecedented gold(i) bioconjugates bearing non-proteinogenic amino acid 4-mercaptoproline species as bioorganic ligands have been prepared. Firstly, the synthesis of Boc-Pro(SH)-OMe (1) has been accomplished by standard procedures. The subsequent reaction of 1 with [AuCl(PR3)] gives complexes Boc-Pro(SAuPR3)-OMe (PR3 = PPh3 (2), PPh2Py (3)). Starting from complex 2 several structural modifications have been performed, in addition to the incorporation of a different phosphine in 3, such as the formation of the acid Boc-Pro(SAuPPh3)-OH (4), the synthesis of a dipeptide derivative by coupling the amino acid glycine tert-butyl ester Boc-Pro(SAuPPh3)-Gly-O(t)Bu (5), or the coordination of another gold phosphine fragment to the sulfur atom as in [Boc-Pro(SAuPPh3)2-OMe]OTf (6). The cytotoxic activity in vitro of these complexes has been evaluated against three different tumor human cell lines, A549 (lung carcinoma), Jurkat (T-cell leukaemia) and MiaPaca2 (pancreatic carcinoma). All the complexes displayed excellent cytotoxic activity with IC50 values in the low µM range and even in the nM range in some cases. Structure-Activity Relationships (SAR) observed from this family of complexes opens the possibility of designing more potent and selective promising gold(i) anticancer agents.

Highly Efficient Catalysis of Retro-Claisen Reactions: From a Quinone Derivative to Functionalized Imidazolium Salts.

A new and efficient method for the preparation of several imidazolium salts containing an ester group in the C4 position of the aromatic ring through a retro-Claisen reaction pathway between a quinone derivative and several alcohols is described. This new organic transformation proceeds in the absence of a catalyst, but it is greatly catalyzed by different Lewis acids, especially with AgOAc at a very low catalyst loading and in very short reaction times. The process takes place by the nucleophilic attack of the carbonyl groups by the alcohol functionality, thus promoting a double C-C bond cleavage and C-H and C-O bond formation. This reaction represents the first example of this type between a quinone derivative and alcohols.

Group 11 complexes with amino acid derivatives: Synthesis and antitumoral studies.

Gold(I), gold(III), silver(I) and copper(I) complexes with modified amino acid esters and phosphine ligands have been prepared in order to test their cytotoxic activity. Two different phosphine fragments, PPh3 and PPh2py (py=pyridine), have been used. The amino acid esters have been modified by introducing an aromatic amine as pyridine that coordinates metal fragments through the nitrogen atom, giving complexes of the type [M(L)(PR3)](+) or [AuCl3(L)] (L=l-valine-N-(4-pyridylcarbonyl) methyl ester (L1), l-alanine-N-(4-pyridylcarbonyl) methyl ester (L2), l-phenylalanine-N-(4-pyridylcarbonyl) methyl-ester) (L3); M=Au(I), Ag(I), Cu(I), PR3=PPh3, PPh2py). The in vitro cytotoxic activity of metal complexes was tested against four tumor human cell lines and one tumor mouse cell line. A metabolic activity test (3-(4,5-dimethyl-thiazol-2-yl)-2,5-diphenyl tetrazolium bromide, MTT) was used and IC50 values were compared with those obtained for cisplatin. Several complexes displayed significant cytotoxic activities. In order to determine whether antiproliferation and cell death are associated with apoptosis, NIH-3T3 cells were exposed to five selected complexes (Annexin V+ FITC, PI) and analyzed by flow cytometry. These experiments showed that the mechanism by which the complexes inhibit cell proliferation inducing cell death in NIH-3T3 cells is mainly apoptotic.

Re(I) derivatives functionalised with thioether crowns containing the 1,10-phenanthroline subunit as a new class of chemosensors.

A series of luminescent fac-[Re(CO)3(L)(NN)](+) complexes, where L is a pyridine or an imidazole and NN is the 1,10-phenanthroline subunit of mixed donor pentadentate thioether crowns have been synthesised and their luminescence properties have been analysed. Then, heterometallic Re(i)/Au(i) complexes, with the Au(i) fragment bonded directly to the imidazole ligand, and heterometallic Re(i)/Ag(i) complexes, with the silver fragment coordinating the S-donor thioether linker of the rings have also been prepared. Analysis of their luminescence properties showed a considerable blue shift of the emission maxima for the Re(i)/Ag(i) derivatives, upon coordination of the silver centre to the S-donor atoms of the aliphatic chain of the macrocyclic units.

Highly cytotoxic bioconjugated gold(I) complexes with cysteine-containing dipeptides.

Several gold(I) complexes with cysteine-containing dipeptides have been prepared starting from cystine by coupling different amino acids and using several orthogonal protections. The first step is the reaction of cystine, where the sulfur centre is protected as disulfide, with Boc2 O in order to protect the amino group, followed by coupling of an amino acid ester; finally the disulfide bridge is broken with mercaptoethanol to afford the dipeptide derivative. Further reaction with [AuCl(PPh3 )] gives the gold-dipeptide-phosphine species. Starting from these formally gold(I) thiolate-dipeptide phosphine complexes with the general formula [Au(SR)(PR3 )] different structural modifications, such as change in the type of the amino protecting group, the type of phosphine, the number of gold(I) atoms per molecule, or the use of a non-proteinogenic conformationally restricted amino acid ester, were introduced in order to evaluate their influence in the biological activity of the final complexes. The cytotoxic activity, in vitro, of these complexes was evaluated against different tumour human cell lines (A549, MiaPaca2 and Jurkat). The complexes show an outstanding cytotoxic activity with IC50 values in the very low micromolar range. Structure-activity relationship studies from the complexes open the possibility of designing more potent and promising gold(I) anticancer agents.

The fluxional amine gold(III) complex as an excellent catalyst and precursor of biologically active acyclic carbenes.

A new amine gold(III) complex [Au(C6F5)2(DPA)]ClO4 with the di-(2-picolyl)amine (DPA) ligand has been synthesised. In the solid state the complex has a chiral amine nitrogen because the ligand coordinates to the gold centre through one nitrogen atom from a pyridine and through the NH moiety, whereas in solution it shows a fluxional behaviour with a rapid exchange between the pyridine sites. This complex can be used as an excellent synton to prepare new gold(III) carbene complexes by the reaction with isocyanide CNR. The resulting gold(III) derivatives have unprecedented bidentate C^N acyclic carbene ligands. All the complexes have been spectroscopically and structurally characterized. Taking advantage of the fluxional behaviour of the amine complex, its catalytic properties have been tested in several reactions with the formation of C-C and C-N bonds. The complex showed excellent activity with total conversion, without the presence of a co-catalyst, and with a catalyst loading as low as 0.1%. These complexes also present biological properties, and cytotoxicity studies have been performed in vitro against three tumour human cell lines, Jurkat (T-cell leukaemia), MiaPaca2 (pancreatic carcinoma) and A549 (lung carcinoma). Some of them showed excellent cytotoxic activity compared with the reference cisplatin.

(Aminophosphane)gold(I) and silver(I) complexes as antibacterial agents.

This manuscript describes the synthesis of new Au(I) and Ag(I) complexes with aminophosphane ligands and a study of their antibacterial activity against Gram-negative Salmonella enterica serovar typhimurium and Escherichia coli and Gram-positive Listeria monocytogenes and Staphylococcus aureus. The bactericidal assays revealed the effectiveness of these compounds on paradigm Gram-negative and Gram-positive pathogens, showing a moderate antimicrobial activity, comparable with the antibiotics of reference, for all gold(I) complexes and the silver(I) complexes without coordinated PPh3 groups. For those complexes that were found to show inhibitory activity, serial dilutions in liquid broth method were performed for determination of MIC (minimum inhibitory concentration) and MBC (minimum bactericidal concentration).

Gold(I) thiolates containing amino acid moieties. Cytotoxicity and structure-activity relationship studies.

Several gold(I) complexes containing a thiolate ligand functionalised with several amino acid or peptide moieties of the type [Au(SPyCOR)(PPh2R')] (where R = OH, amino acid or dipeptide and R' = Ph or Py) were prepared. These thiolate gold complexes bearing biological molecules possess potential use as antitumor agents. Cytotoxicity assays in different tumour cell lines such as A549 (lung carcinoma), Jurkat (T-cell leukaemia) and MiaPaca2 (pancreatic carcinoma) revealed that the complexes exhibit good antiproliferative activity, with IC50 values in the low micromolar range. Several structural modifications such as in the type of phosphine, number of metal atoms and amino acid (type, stereochemistry and functionalisation) were carried out in order to establish the structure-activity relationship in this family of complexes, which has led to the design of new and more potent cytotoxic complexes. Observations of different cellular events after addition of the complexes indicated the possible mechanism of action or the biological targets of this type of new gold(I) drug.

Axially chiral allenyl gold complexes.

Unprecedented allenyl gold complexes have been achieved starting from triphenylpropargylphosphonium bromide. Two different coordination modes of the allene isomer of triphenylphosphoniumpropargylide to gold have been found depending on the gold oxidation state. Bromo-, pentafluorophenyl-, and triphenylphosphine-gold(I) allenyl complexes were prepared in which the α carbon coordinates to the gold(I) center. A chiral pentafluorophenyl-gold(III) allenyl complex with the gold atoms coordinated to the γ carbon was also prepared. All the complexes have been structurally characterized by X-ray diffraction showing the characteristic distances for a C═C═C unit.

Luminescent gold and silver complexes with the monophosphane 1-(PPh2)-2-Me-C2B10H10 and their conversion to gold micro- and superstructured materials.

Gold and silver complexes containing the monophosphane 1-PPh2-2-Me-l,2-C2B10H10 with different coordination numbers (2, 3) have been synthesized: [M(7,8-(PPh2)2-C2B9H10)(1-PPh2-2-Me-C2B10H10)] (M = Ag, Au) and [Au2(µ-1,n-C2B10H10)(1-PPh2-2-Me-C2B10H10)2] (n = 2, 12). Solid-state pyrolysis of [AuCl(1-PPh2-2-Me-C2B10H10)] and [Au2(µ-1,12-C2B10H10)(1-PPh2-2-Me-C2B10H10)2] in air and of solutions of [AuCl(1-PPh2-2-Me-C2B10H10)] deposited on silicon and silica at 800 °C results in single-crystal Au, confirmed by diffraction and SEM-EDS. The morphology of the pyrolytic products depends on the thermolytic conditions, and different novel 3-D superstructures or microcrystals are possible. We also propose a mechanism for the thermal conversion of these precursors to structural crystalline and phase pure materials. The presence of the carborane monophosphane seems to originate quenching of the luminescence at room temperature in the complexes [Au2(µ-1,n-C2B10H10)(1-PPh2-2-Me-C2B10H10)2], in comparison with other [Au2(µ-1,n-C2B10H10)L2] species (L = monophosphane).

A comparative study of structural patterns and luminescent properties of silver-DAFO complexes with carborane- versus "classical"-diphosphanes.

New complexes with the DAFO (4,5-diazafluoren-9-one) ligand of stoichiometry [Ag(DAFO)(P-P)]OTf [P-P = dppe, 1,2-bis(diphenylphosphane)ethane; dppp, 1,3-bis(diphenylphosphane)propane; dppph, ortho-bis(diphenylphosphane)benzene; dppcc, 1,2-bis(diphenylphosphane)-1,2-dicarba-closo-dodecaborane; dipcc, 1,2-bis(diisopropylphosphane)-1,2-dicarba-nido-dodecaborane], [Ag(DAFO)(P-P*)] [P-P* = dppnc, 7,8-bis(diphenylphosphane)-7,8-dicarba-nido-undecaborate(-1); dipnc, 7,8-bis(diisopropylphosphane)-7,8-dicarba-closo-undecaborate(-1)] and [Ag(DAFO)(OTf)L] [L = PPh3; dpccMe, 1-diphenylphosphane-2-methyl-1,2-dicarba-closo-dodecaborane] are reported. The structures of the complexes depend on the skeleton of the diphosphane. Most of these compounds are luminescent and their emissions seem to have originated from IL (DAFO) transitions, modified upon coordination to silver.

Different emissive properties in dithiolate gold(i) complexes as a function of the presence of phenylene spacers.

A family of dinuclear neutral thiolate gold complexes of the type RPh2PAuS(C6H4)nSAuPPh2R (n = 2, 3), RPh2PAuS(C6H4)S(C6H4)SAuPPh2R, RPh2PAuSCH2(C6H4)2CH2SAuPPh2R where R represents a pyridine or a phenylene ring, has been prepared and fully characterized. X-ray crystallographic studies showed the presence of aurophilic interactions for those species bearing two phenylene spacers between the gold metal centers, leading to infinite chains. The complexes are emissive in the solid state. Theoretical calculations together with the photophysical analysis seem to indicate that the main excitations involved in the emissive processes are due to a mixture of ILCT transition involving the thiolate and the conjugated phenylene rings, and LL'CT transitions comprising the thiolate and the pyridine or phenyl from the phosphine fragment which contrast with the typical gold thiolate emission, LMCT from the thiolate fragment to the metal center.