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Many metabolites are generated in one step of a biochemical pathway and consumed in a subsequent step. Such metabolic intermediates are often reactive molecules which, if allowed to freely diffuse in the intracellular milieu, could lead to undesirable side reactions and even become toxic to the cell. Therefore, metabolic intermediates are often protected as protein-bound species and directly transferred between enzyme active sites in multi-functional enzymes, multi-enzyme complexes, and metabolons. Sequestration of reactive metabolic intermediates thus contributes to metabolic efficiency. It is not known, however, whether this evolutionary adaptation can be relaxed in response to challenges to organismal survival. Here, we report evolutionary repair experiments on Escherichia coli cells in which an enzyme crucial for the biosynthesis of proline has been deleted. The deletion makes cells unable to grow in a culture medium lacking proline. Remarkably, however, cell growth is efficiently restored by many single mutations (12 at least) in the gene of glutamine synthetase. The mutations cause the leakage to the intracellular milieu of a highly reactive phosphorylated intermediate common to the biosynthetic pathways of glutamine and proline. This intermediate is generally assumed to exist only as a protein-bound species. Nevertheless, its diffusion upon mutation-induced leakage enables a new route to proline biosynthesis. Our results support that leakage of sequestered metabolic intermediates can readily occur and contribute to organismal adaptation in some scenarios. Enhanced availability of reactive molecules may enable the generation of new biochemical pathways and the potential of mutation-induced leakage in metabolic engineering is noted.
Subject(s)
Biological Evolution , Biosynthetic Pathways , Cell Survival , Mutation , ProlineABSTRACT
The development of chiral compounds with enhanced chiroptical properties is an important challenge to improve device applications. To that end, an optimization of the electric and magnetic dipole transition moments of the molecule is necessary. Nevertheless, the relationship between chemical structure and such quantum mechanical properties is not always clear. That is the case of magnetic dipole transition moment (m) for which no general trends for its optimization have been suggested. In this work we propose a general rationalization for improving the magnitude of m in different families of chiral compounds. Performing a clustering analysis of hundreds of transitions, we have been able to identify a single group in which |m| value is maximized along the helix axis. More interestingly, we have found an accurate linear relationship (up to R2 =0.994) between the maximum value of this parameter and the area of the inner cavity of the helix, thus resembling classical behavior of solenoids. This research provides a tool for the rationalized synthesis of compounds with improved chiroptical responses.
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A new linear trinuclear Co(II)3 complex with a formula of [{Co(µ-L)}2Co] has been prepared by self-assembly of Co(II) ions and the N3O3-tripodal Schiff base ligand H3L, which is obtained from the condensation of 1,1,1-tris(aminomethyl)ethane and salicylaldehyde. Single X-ray diffraction shows that this compound is centrosymmetric with triple-phenolate bridging groups connecting neighboring Co(II) ions, leading to a paddle-wheel-like structure with a pseudo-C3 axis lying in the Co-Co-Co direction. The Co(II) ions at both ends of the Co(II)3 molecule exhibit distorted trigonal prismatic CoN3O3 geometry, whereas the Co(II) at the middle presents an elongated trigonal antiprismatic CoO6 geometry. The combined analysis of the magnetic data and theoretical calculations reveal strong easy-axis magnetic anisotropy for both types of Co(II) ions (|D| values higher than 115 cm-1) with the local anisotropic axes lying on the pseudo-C3 axis of the molecule. The magnetic exchange interaction between the middle and ends Co(II) ions, extracted by using either a Hamiltonian accounting for the isotropic magnetic coupling and ZFS or the Lines' model, was found to be medium to strong and antiferromagnetic in nature, whereas the interaction between the external Co(II) ions is weak antiferromagnetic. Interestingly, the compound exhibits slow relaxation of magnetization and open hysteresis at zero field and therefore SMM behavior. The significant magnetic exchange coupling found for [{Co(µ-L)}2Co] is mainly responsible for the quenching of QTM, which combined with the easy-axis local anisotropy of the CoII ions and the collinearity of their local anisotropy axes with the pseudo-C3 axis favors the observation of SMM behavior at zero field.
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The auditory N1 component has been gaining interest as a possible biomarker in schizophrenia (SCZ). N1 to right (RE) and left ear (LE) amplitudes and latencies were assessed using a monoaural auditory oddball paradigm in 12 SCZ subjects and 15 matched healthy controls (M=40.1±8.53 and 39.4±7.73, respectively). T-student test revealed no differences between RE and LE stimulation for N1 amplitude and latency to both groups. However, there were differences in peak-to-peak N1 amplitudes between the two groups for both LE (t=-3.067; ρ=0.003) and RE (t=-2.794; ρ=0.007). These findings strengthen auditory N1 has an electrophysiological biomarker for schizophrenia.
Subject(s)
Evoked Potentials, Auditory , Schizophrenia , Biomarkers , Electroencephalography , Humans , Reaction Time , Schizophrenia/diagnosisABSTRACT
AIM: The aim of this study was to compare the outcomes, patterns of failure and laryngeal preservation rates in patients with T1N0 glottic cancer treated with surgery or radiotherapy. MATERIALS/METHODS: Retrospective study of T1N0 glottic cancer patients treated in our institution between January 2007 and December 2017. Histologically proven squamous cell carcinoma patients, treated with upfront cordectomy/partial laryngectomy (S group) or radiotherapy (RT group) were included. Elective treatment of the neck was not permitted. Local failure (LF), disease-free survival (DFS), ultimate disease-free survival (UDFS), laryngectomy-free survival (LFS), disease-specific mortality (DSM) and overall survival (OS) were evaluated. RESULTS: Two hundred and one patients were eligible (172 S group, 29 RT group), with a median follow-up of 38.8 months. Overall, 33 (16%) patients had a recurrence, 30 (17%) in the S group and 3 (10%) in the RT group. Local failure was the predominant site of failure (28 S, 2 RT). Overall, of all those that were salvaged, 17 (8%) underwent total laryngectomy (15 S, 2 RT). There was no significant difference in the 5-year cumulative incidence of LF (20.8% S, 8.1% RT, p = 0.138), 5-y LFS (85.0% vs. 91.7%, p = 0.809), 5-y DFS (67.5% vs. 82.1%, p = 0.343), 5-y UDFS (82.5% vs. 90.3%, p = 0.647) and 5-y OS (84.5% vs. 90.3%, p = 0.892). Multivariate analysis showed no correlation between initial treatment and the analyzed outcomes. CONCLUSION: Primary surgery or radiotherapy were similar first line options, since they do not differ in all outcomes. Patients' and physician's preferences must be considered when choosing first treatment.
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PURPOSE: Report our matured outcomes of European nasopharyngeal carcinoma (NPC) treatment from a non-endemic region in the IMRT era. METHODS: We reviewed 109 consecutive patients with biopsy proven NPC treated between 2009 and 2013. All received IMRT as per RTOG 0615. Toxicity was scored accordingly to CTCAE 4.03. Platinum-based chemotherapy was delivered following the Intergroup 0099. RESULTS: Median age of 53 years; 97% Caucasian; 74% male; 72% WHO grade III; 43% T1; 14% T2; 18% T3, 25% T4; 17% N0; 17% N1; 39% N2; 27% N3. Compliance to adjuvant chemotherapy was 88%. With a median follow up of 56 months, the 4-year local control was 90.2% (88.6% for T1; 100% for T2; 85% for T3; and 91.7% for T4), the 4-year distant metastases-free survival was 86% and an overall survival rate was 77%. Local control and survival were better in G3 (pâ¯<â¯0.001 and pâ¯=â¯0.032, respectively). Xerostomia was the most frequent late toxicity in 55% (nâ¯=â¯60). Hypothyroidism requiring hormonal reposition occurred in 15.5% (nâ¯=â¯17). From the 36 deaths, 20 were due to distant metastases, 3 grade 5 toxicity, 2 from local progression, 5 non-cancer deaths and unknown cause in the remaining 6. On multivariable analysis, age (pâ¯=â¯0.017), local recurrence and distant metastases were associated with death (pâ¯<â¯0.001, both). CONCLUSION: Our matured data from the IMRT era showed a major improvement from our 3D cohort series reaching excellent local and regional control, even in T4. Local recurrences, despite few, and distant metastases were correlated with the risk of death.
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In this work we describe the ability of a simple enantiopure sulfoxide group to promote folding of oligo ortho-phenylene ethynylenes (o-OPEs) with one helical sense. A family of foldamers with up to seven triple bonds was synthesized and fully characterized. Moreover, changes in structure and chiroptical properties caused by Ag(i) coordination have been studied by NMR, UV, VCD and ECD measurements. Quantum mechanical DFT calculations support experimental results.
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A new family of homochiral silver complexes based on carbophilic interactions with ortho-phenylene ethynylene (o-OPE) scaffolds containing up to two silver atoms are described. These compounds represent a unique class of complexes with chirality at the metal. Chiral induction is based on the inclusion of chiral sulfoxides, which allow efficient transfer of chirality to the helically folded o-OPE, leading to circularly polarized luminescence (CPL)- and vibrational circular dichroism (VCD)-active compounds. In the presence of silver(I) cations, carbophilic interactions dominate, which promote helical structures with a defined helicity. This is one of the very scarce examples of the use of such interactions in the attractive field of abiotic foldamers. The switching event has been extensively studied by using different chiroptical techniques, including circular dichroism, CPL, and VCD, and represents one of the few CPL switches described in the literature.
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A new dinuclear complex [{Fe(tpc-OBn)(NCS)(µ-NCS)}2] (1) based on the tripodal tpc-OBn ligand (tpc-OBn = tris(2-pyridyl)benzyloxymethane), containing bridging µ-κN:κS-SCN and terminal κN-SCN thiocyanate ligands, has been prepared and characterized by single crystal X-ray diffraction, magnetic studies, and DFT theoretical calculations. This complex represents the first example of dinuclear FeII complex with double µ-κN:κS-SCN bridges in a head-to-tail configuration that exhibits ferromagnetic coupling between metal ions (JFeFe = +1.08 cm-1). Experimental and theoretical magnetostructural studies on this kind of infrequent FeII dinuclear complex containing a centrosymmetrically [Fe2(µ-SCN)2] bridging fragment show that the magnitude and sign of the magnetic coupling parameter, JFeFe, depend to a large extent on the Fe-N-C (α) angle, so that JFeFe decreases linearly when α decreases. The calculated crossover point below which the magnetic interactions change from ferromagnetic to antiferromagnetic is found at 162.3°. In addition, experimental results obtained in this work and those reported in the literature suggest that large Ntripodal-FeII distances and bent N-bound terminal κN-SCN ligands favor the high spin state of the FeII ions, while short Ntripodal-FeII distances and almost linear Fe-N-C angles favor a stronger ligand field, which enables the FeII ions to show spin crossover (SCO) behavior.
ABSTRACT
We present here a novel example of spin crossover phenomenon on a Fe(II) one-dimensional chain with unusual N5S coordination sphere. The [{Fe(tpc-OMe)(NCS)(µ-NCS)} n] (1) compound was prepared using the tridentate tpc-OMe ligand (tpc-OMe = tris(2-pyridyl)methoxymethane), FeCl2·4H2O, and the KSCN salt. Crystallographic investigations revealed that the Fe(II) ions are connected by a single bridging NCS- ligand (µ-κN:κS-SCN coordination mode) to afford a zigzag neutral chain running along the [010] direction, in which the thiocyanato bridging groups adopt a cis head-to-tail configuration. The (N5S) metal environment arises from one thiocyanato-κS and two thiocyanato-κN ligands and from three pyridine of the fac-tpc-OMe tripodal ligand. This compound presents a unique extension of Fe(II) binuclear complexes into linear chains built on similar tripodal ligands and bridging thiocyanate anions. Compound 1 shows a spin crossover (SCO) behavior which has been evidenced by magnetic, calorimetric, and structural investigations, revealing a sharp cooperative spin transition with a transition temperature of ca. 199 K. Temperature scan rate studies revealed a very narrow hysteresis loop (â¼1 K wide). Photoswitching of this compound was also performed, evidencing a very fast relaxation process at low temperature. Among other factors, the linearity of the N-bound terminal thiocyanato ligand appears as the main structural characteristic at the origin of the presence of the SCO transition in compound 1 and in the two others Fe(II) previous systems involving thiocyanato-bridges and tripodal tris(2-pyridyl)methane ligands.
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Acyl(σ-norbornenyl)rhodium(III) dimer [Rh(µ-Cl)(C9H6NCO)(C7H9)L]2 (1) (C7H9 = σ-norbornenyl; L = 4-picoline, isoquinoline) reacts with diphenylphosphine oxide (SPO) to undergo a one-pot reaction involving (i) cleavage of the chloride bridges and coordination of the phosphine, (ii) C-C bond coupling between acyl and norbornenyl in a 18e species, and (iii) ligand-assisted outer-sphere O(P)-to-O(C) hydrogen transfer, to afford mononuclear 16e species [RhCl{(C9H6NC(O)C7H9)(Ph2PO)H}(L)] (2) containing a quinolinyl-(norbornenylhydroxyalkyl) fragment hydrogen-bonded to a κ1- P-phosphinite ligand. Pentacoordinated 2, which adopt a distorted trigonal bipyramidal structure, are kinetic reaction products that transform into the thermodynamic favored isomers 3. Structures 3 contain an unusual weak η1-C anagostic interaction involving the rhodium atom and one carbon atom of the olefinic C-H bond of the norbornenyl substituent in the chelating quinolinyl-hydroxyalkyl moiety. Their structure can be described as pseudoctahedral, through a 5 + 1 coordination, with the anagostic interaction in a trans disposition with respect to the phosphorus atom of the phosphinite ligand. Complexes were characterized in solution by NMR spectroscopy and electrospray ionization mass spectrometry. Complex [RhCl{(C9H6NC(O)C7H9)(Ph2PO)H}(4-picoline)] (3a) was also identified by X-ray diffraction. Density functional theory calculations confirm the proposed structures by a plausible set of mechanisms that accounts for the 1 (monomer) â 2 â 3 transformation. Lowest-energy pathways involve reductive elimination of quinolinylnorbornenylketone, still coordinated in the rhodium(I) species thus formed, followed by O-to-O hydrogen transfer from κ1- P-SPO to the sp3 hybridized carbonyl group (formal alkoxide) avoiding the otherwise expected classical release of ketone. Theoretical 13C NMR studies also confirm the experimental spectral data for the considered structures.
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A family of MnIIILnIII strictly dinuclear complexes of general formula [MnIII(µ-L)(µ-OMe)(NO3)LnIII(NO3)2(MeOH)] (LnIII = Gd, Dy, Er, Ho) has been assembled in a one pot synthesis from a polydentate, multipocket aminobis(phenol)ligand [6,6'-{(2-(1-morpholyl)ethylazanediyl)bis(methylene)}bis(2-methoxy-4-methylphenol)], Mn(NO3)2·4H2O, Ln(NO3)3· nH2O, and NEt3 in MeOH. These compounds represent the first examples of fully structurally and magnetically characterized dinuclear MnIIILnIII complexes. Single X-ray diffraction studies reveal that all complexes are isostructural, consisting of neutral dinuclear molecules where the MnIII and LnIII metal ions, which exhibit distorted octahedral MnN2O4 and distorted LnO9 coordination spheres, are linked by phenoxide/methoxide double bridging groups. Static magnetic studies show that the MnIIIGdIII derivative exhibits a weak antiferromagnetic interaction between the metal ions, with a negative axial zero-field splitting D parameter. The MnIIIGdIII complex shows a notable magnetocaloric effect with magnetic entropy change at 5 T and 3 K of -Δ Sm = 16.8 J kg-1 K-1. Theoretical studies were performed to support the sign and magnitude of the magnetic anisotropy of the MnIII ion ( ab initio), to predict the value and nature of JMnGd, to disclose the mechanism of magnetic coupling, and to establish magneto-structural correlations (DFT calculations). The results of these calculations are corroborated by quantum theory of atoms in molecule analysis (QTAIM). Finally, MnIII-DyIII and MnIII-ErIII complexes show field-induced slow relaxation of the magnetization but without reaching a maximum above 2 K in the out-of-phase ac susceptibility. Ab initio calculations were also performed on MnIII-DyIII/HoIII systems to unravel the origin behind the weak SMM characteristics of the molecules possessing two strongly anisotropic ions. The mechanism of magnetic relaxation was developed, revealing a large QTM/tunnel splitting at the single-ion level. Furthermore, the anisotropy axes of the MnIII and LnIII ions were calculated to be noncollinear, leading to reduction of the overall anisotropy in the molecules. Hence, the herein reported complexes demonstrate that a combination of two anisotropic metal ions does not guarantee SMM behavior.
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Conformational mobility is a core property of organic compounds, and conformational analysis has become a pervasive tool for synthetic design. In this work, we present experimental and computational (employing Density Functional Theory) evidence for unusual intramolecular hydrogen bonding interactions in a series of α-acylmethane derivatives, as well as a discussion of the consequences thereof for their NMR spectroscopic properties.
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The design of two dimensional graphene-type materials with an anisotropic electron flow direction in the X- and Y-axes opens the door for the development of novel electronic materials with multiple functions in nanoelectronics. In the present work, we have studied the electronic transport properties of a new family of 2D graphene-graphyne hybrids presenting conformationally free phenylethylene subunits. This system ensures two different conductive pathways that are perpendicular to each other: an acene nanoribbon subunit, in the X-axis, with graphene-type conduction, and a free to rotate phenylethylene subunit, in the Y-axis, in which the magnitude of the conduction depends dynamically on the corresponding torsion angle. Our calculations have confirmed that this system presents two different conduction pathways, which are related to the presence of asymmetric Dirac-type cones. Moreover, the Dirac cones can be dynamically modified in the presence of an external gate electrode, which is unprecedented in the literature.
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We describe a new strategy to control the number of cyclization steps in bioinspired radical (poly)cyclizations involving epoxypolyenes containing keto units positioned along the polyene chain. This approach provides an unprecedentedly straightforward access to natural terpenoids with pendant unsaturated side chains. Additionally, in the case of bi- and tricyclizations, decalins with cis stereochemistry have been obtained as a consequence of the presence of the ketone. The preferential formation of cis-fused adducts was rationalized using DFT calculations. This result is completely unprecedented in biomimetic cyclizations and permits the access to natural terpenoids with this stereochemistry, as well as to non-natural analogues.
Subject(s)
Epoxy Compounds/chemistry , Polyenes/chemistry , Titanium/chemistry , Catalysis , Cyclization , Ketones/chemistry , Models, Molecular , Quantum Theory , StereoisomerismABSTRACT
Two series of isostructural C(3)-symmetric Ln(3) complexes Ln(3)â [BPh(4)] and Ln(3)â 0.33[Ln(NO(3))(6)] (in which Ln(III) =Gd and Dy) have been prepared from an amino-bis(phenol) ligand. X-ray studies reveal that Ln(III) ions are connected by one µ(2)-phenoxo and two µ(3)-methoxo bridges, thus leading to a hexagonal bipyramidal Ln(3)O(5) bridging core in which Ln(III) ions exhibit a biaugmented trigonal-prismatic geometry. Magnetic susceptibility studies and ab initio complete active space self-consistent field (CASSCF) calculations indicate that the magnetic coupling between the Dy(III) ions, which possess a high axial anisotropy in the ground state, is very weakly antiferromagnetic and mainly dipolar in nature. To reduce the electronic repulsion from the coordinating oxygen atom with the shortest Dy-O distance, the local magnetic moments are oriented almost perpendicular to the Dy(3) plane, thus leading to a paramagnetic ground state. CASSCF plus restricted active space state interaction (RASSI) calculations also show that the ground and first excited state of the Dy(III) ions are separated by approximately 150 and 177â cm(-1), for Dy(3)â [BPh(4)] and Dy(3)â 0.33[Dy(NO(3))(6)], respectively. As expected for these large energy gaps, Dy(3)â [BPh(4)] and Dy(3)â 0.33[Dy(NO(3)(6)] exhibit, under zero direct-current (dc) field, thermally activated slow relaxation of the magnetization, which overlap with a quantum tunneling relaxation process. Under an applied Hdc field of 1000â Oe, Dy(3)â [BPh(4)] exhibits two thermally activated processes with U(eff) values of 34.7 and 19.5â cm(-1), whereas Dy(3)â 0.33[Dy(NO(3))(6)] shows only one activated process with Ueff =19.5â cm(-1).
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Objective To report the outcomes with high-dose-rate (HDR) brachytherapy (BT) treatment in patients with lower eyelid basal cell carcinoma (BCC) and to evaluate the relationship between dosimetric parameters and acute and late toxicities. Material and methods A retrospective unicentric study with patients diagnosed with lower eyelid biopsy-proven BCC treated with HDR BT between January 2012 and December 2019. The prescribed dose was 36 Gy to 40 Gy in 9 to 10 fractions, twice daily, over five days. The primary endpoint was local control, and the secondary endpoints were acute and late toxicities, registered according to CTCAE v4.0. The cosmetic result was evaluated on a qualitative scale (the CAIB scale). Local control was calculated according to the Kaplan-Meier test. Two sample T-tests and a Wilcoxon signed-rank test were used to determine the association between dosimetric parameters and side effects. Results Fifty-eight patients with a median age of 76 years were included. Among these patients, 55.2% received adjuvant HDR BT and 44.8% received radical HDR BT. At a median follow-up of 44 months, there were four local relapses, achieving a probability of local control at four years of 95% and 100% in the adjuvant and radical groups, respectively. Acute toxicity occurred in 76% of patients with only one grade 3 event (radiation dermatitis). Late toxicity was present in 56%. Eight patients underwent treatment for grade 3 cataracts during follow-up. Cosmetic results were excellent or very good in 93% of patients. Acute conjunctival hyperemia is strongly associated with the dose received by the ocular globe (volumes of 0.1cc, 1cc, and 2 cc) (p<0.05). Conclusion Lower eyelid BCC treatment with interstitial HDR BT is associated with excellent local control, acceptable long-term side effects, and good cosmetic results.
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The reaction of the multisite coordination ligand (LH4) with CoX2·nH2O in the presence of tetrabutylammonium hydroxide affords a series of homometallic dinuclear mixed-valence complexes, [Co(III)Co(II)(LH2)2(X)(H2O)](H2O)m (1, X = Cl and m = 4; 2, X = Br and m = 4; 3, X = NO3 and m = 3). All of the complexes have been structurally characterized by X-ray crystallography. Both cobalt ions in these dinuclear complexes are present in a distorted-octahedral geometry. Detailed magnetic studies on 1-3 have been carried out. M vs H data at different temperatures can be fitted with S = 3/2, the best fit leading to D(3/2) = -7.4 cm(-1), |E/D| < 1 × 10(-3), and g = 2.32 for 1 and D(3/2) = -9.7 cm(-1), |E/D| <1 × 10(-4), and g = 2.52 for 2. In contrast to 1 and 2, M vs H data at different temperatures suggest that compound 3 has comparatively little magnetic anisotropy. In accordance with the large negative D values observed for compounds 1 and 2, they are single-molecule magnets (SMMs) and exhibit slow relaxation of magnetization at low temperatures under an applied magnetic field of 1000 Oe with the following energy barriers: 7.9 cm(-1) (τo = 6.1 × 10(-6) s) for 1 and 14.5 cm(-1) (τo = 1.0 × 10(-6) s) for 2. Complex 3 does not show any SMM behavior, as expected from its small magnetic anisotropy. The τo values observed for 1 and 2 are much larger than expected for a SMM, strongly suggesting that the quantum pathway of relaxation at very low temperatures is not fully suppressed by the effects of the applied field.
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The µ4-hydroxo- and alkoxo-bridged tetranuclear copper(II) complexes, [Cu4(µ4-OH)(dmae)4][Ag(NO3)4] (1), [Cu4(µ4-OH)(dmae)4][Na(NO3)4] (2), [Cu4(µ4-OH)(dmae)4][K(NO3)4] (3), and hexanuclear alkoxo-bridged "bicapped cubane" copper(II) complex [Cu6(ae)8(ClO4)2](ClO4)2·MeOH (8) (dmae = N,N-dimethylaminoethanolato and ae = 2-aminoethanolato) were synthesized via self-assembly from chelating amino alcohols and copper(II), silver (1), sodium (2), and potassium (3) nitrates or copper(II) perchlorate (8). The complexes are characterized by elemental analyses, single-crystal X-ray diffraction, and variable temperature magnetic measurements. The crystal structures of complexes 1-3 consist of almost planar tetranuclear [Cu4(µ4-OH)(dmae)4](3+) units, in which Cu(II) ions are also weakly bonded to nitrate anions. The adjacent tetranuclear units of 1-3 are connected by ionic interactions between nitrate anions and sodium, potassium, or silver cations resulting in the formation of 1D polymers. The crystal structure of 8 consists of hexanuclear [Cu6(ae)8](4+) "bicapped cubane" units, in which the capping Cu(II) ions are weakly bonded to perchlorate anions. The adjacent hexanuclear units of 8 are connected by hydrogen bonds resulting in the formation of 3D hydrogen bonded networks. Also the results from the synthetic studies leading to the formation of new copper(II) and silver(I) complexes (4-7) using Hae, 3-aminopropanol (Hap), and N,N-dimethylaminopropanol (Hdmap) in similar reactions, which gave tetra- and hexanuclear complexes, are presented. Experimental magnetic studies showed that complexes 1 and 2 exhibit dominant antiferromagnetic coupling leading to an S = 0 ground state, whereas 8 exhibits a large dominant antiferromagnetic interaction between the capping copper atoms and the copper atoms of the top and bottom faces of the cubane unit that define two isosceles triangles. This interaction leads to an S = 1/2 ground state for each triangle. The weak ferromagnetic interaction between these doublet states through the cubane unit leads to a triplet S = 1 ground state for 8. The values of the magnetic exchange coupling constant were the following: J = +1.8 (1) and +2.9 cm(-1) (2) between adjacent copper atoms; J' = -29.2 (1) and -32.2 cm(-1) (2) between opposite copper atoms; J = -297.6 cm(-1) and zJ' = +0.07 cm(-1) (8). Magnetic coupling constants calculated for 2 and 8 by DFT methods are in general of the same nature and magnitude as the experimental ones.
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A series of six mixed-valence Mn(II)/Mn(III) dinuclear complexes were synthesized and characterized by X-ray diffraction. The reactivity of the complexes was surveyed, and structures of three additional trinuclear mixed-valence Mn(III)/Mn(II)/Mn(III) species were resolved. The magnetic properties of the complexes were studied in detail both experimentally and theoretically. All dinuclear complexes show ferromagnetic intramolecular interactions, which were justified on the basis of the electronic structures of the Mn(II) and Mn(III) ions. The large Mn(II)-O-Mn(III) bond angle and small distortion of the Mn(II) cation from the ideal square pyramidal geometry were shown to enhance the ferromagnetic interactions since these geometrical conditions seem to favor the orthogonal arrangement of the magnetic orbitals.