Defining the latent phase of labour: is it important?

Background and rationale. The latent phase of labour is recognised as a period of uncertainty for women and midwives. There is evidence from the literature of considerable variation in labour definitions and practice. Stimulated by discussion at an international maternity research conference, the authors set out to explore opinions regarding the need for labour-stage definitions.  Aim. To identify health professionals’ views on the need for a definition of the onset and the end of the latent phase of labour.  Methods. This was an opportunistic, semi-structured, online survey of attendees at a maternity care research conference, which included midwives, other clinicians, academics, advocates and user representatives. Attendees (approximately 100) were invited to participate through a single email invitation sent by the conference committee and containing a link to the survey. Consent was sought on the landing page. Ethical approval was obtained from Bournemouth University’s research ethics committee. Quantitative questions were analysed using simple descriptive statistics using IBM SPSS Statistics Version 24. Open questions were analysed using content analysis and where participants gave a more detailed answer, these were analysed using a thematic approach.  Findings. Participants in the survey (n=21) came from 12 countries. Most of the participants thought that there was a need to define the onset of the latent phase (n=15, 71%). Common characteristics were cited, but the main theme in the open comments referred to the importance of women’s perceptions of labour onset. Most participants (n = 18, 86%) thought that there was a need to define the end of the latent phase. This was felt necessary because current practice within facilities is usually dictated by a definition. The characteristics suggested were also not unexpected and there was some consensus; but the degree of cervical dilatation that signified the end of the latent phase varied among participants. There was significant debate about whether a prolonged latent phase was important; for example, was it associated with adverse consequences. Most participants thought it was important (n=15, 71%), but comments indicated that the reasons for this were complex. Themes included the value that women attached to knowing the duration of labour and the need to support women in the latent phase.  Implications for practice. The findings from this small, opportunistic survey reflect the current debate within the maternal health community regarding the latent phase of labour. There is a need for more clarity around latent phase labour (in terms of both the definition and the support offered) if midwives are to provide care that is both woman centred and evidence-based. The findings will inform the development of a larger survey to explore attitudes towards labour definitions

Scan Rate Dependent Spin Crossover Iron(II) Complex with Two Different Relaxations and Thermal Hysteresis <i>fac</i>-[Fe^II(HL^{<i>n</i>‑Pr})₃]Cl·PF₆ (HL^{<i>n</i>‑Pr} = 2‑Methylimidazol-4-yl-methylideneamino‑<i>n</i>‑propyl)

Solvent-free spin crossover Fe^II complex <i>fac</i>-[Fe^II(HL^{<i>n</i>‑Pr})₃]­Cl·PF₆ was prepared, where HL^{<i>n</i>‑Pr} denotes 2-methylimidazol-4-yl-methylideneamino-<i>n</i>-propyl. The magnetic susceptibility measurements at scan rate of 0.5 K min^–1 showed two successive spin transition processes consisting of the first spin transition <i>T</i>₁ centered at 122 K (<i>T</i>_1↑ = 127.1 K, <i>T</i>_1↓ = 115.8 K) and the second spin transition <i>T</i>₂ centered at ca. 105 K (<i>T</i>_2↑ = 115.8 K, <i>T</i>_2↓ = 97.2 K). The magnetic susceptibility measurements at the scan rate of 2.0, 1.0, 0.5, 0.25, and 0.1 K min^–1 showed two scan speed dependent spin transitions, while the Mössbauer spectra detected only the first spin transition <i>T</i>₁. The crystal structures were determined at 160, 143, 120, 110, 95 K in the cooling mode, and 110, 120, and 130 K in the warming mode so as to follow the spin transition process of high-spin HS → HS­(<i>T</i>₁) → HS­(<i>T</i>₂) → low-spin LS → LS­(<i>T</i>₂) → LS­(<i>T</i>₁) → HS. The crystal structures at all temperatures have a triclinic space group <i>P</i>1̅ with <i>Z</i> = 2. The complex-cation has an octahedral N₆ coordination geometry with three bidentate ligands and assume a <i>facial</i>-isomer with Δ- and Λ-enantimorphs. Three imidazole groups of <i>fac</i>-[Fe^II(HL^{<i>n</i>‑Pr})₃]²⁺ are hydrogen-bonded to three Cl^– ions. The 3:3 NH­(imidazole)···Cl^– hydrogen-bonds form a stepwise ladder assembly structure, which is maintained during the spin transition process. The spin transition process is related to the structural changes of the FeN₆ coordination environment, the order–disorder of PF₆^– anion, and the conformation change of <i>n</i>-propyl groups. The Fe–N bond distance in the HS state is longer by 0.2 Å than that in the LS state. Disorder of PF₆^– anion is not observed in the LS state but in the HS state. The conformational changes of <i>n</i>-propyl groups are found in the spin transition processes except for HS → HS­(<i>T</i>₁) → HS­(<i>T</i>₂)

Scan Rate Dependent Spin Crossover Iron(II) Complex with Two Different Relaxations and Thermal Hysteresis <i>fac</i>-[Fe^II(HL^{<i>n</i>‑Pr})₃]Cl·PF₆ (HL^{<i>n</i>‑Pr} = 2‑Methylimidazol-4-yl-methylideneamino‑<i>n</i>‑propyl)

Solvent-free spin crossover Fe^II complex <i>fac</i>-[Fe^II(HL^{<i>n</i>‑Pr})₃]­Cl·PF₆ was prepared, where HL^{<i>n</i>‑Pr} denotes 2-methylimidazol-4-yl-methylideneamino-<i>n</i>-propyl. The magnetic susceptibility measurements at scan rate of 0.5 K min^–1 showed two successive spin transition processes consisting of the first spin transition <i>T</i>₁ centered at 122 K (<i>T</i>_1↑ = 127.1 K, <i>T</i>_1↓ = 115.8 K) and the second spin transition <i>T</i>₂ centered at ca. 105 K (<i>T</i>_2↑ = 115.8 K, <i>T</i>_2↓ = 97.2 K). The magnetic susceptibility measurements at the scan rate of 2.0, 1.0, 0.5, 0.25, and 0.1 K min^–1 showed two scan speed dependent spin transitions, while the Mössbauer spectra detected only the first spin transition <i>T</i>₁. The crystal structures were determined at 160, 143, 120, 110, 95 K in the cooling mode, and 110, 120, and 130 K in the warming mode so as to follow the spin transition process of high-spin HS → HS­(<i>T</i>₁) → HS­(<i>T</i>₂) → low-spin LS → LS­(<i>T</i>₂) → LS­(<i>T</i>₁) → HS. The crystal structures at all temperatures have a triclinic space group <i>P</i>1̅ with <i>Z</i> = 2. The complex-cation has an octahedral N₆ coordination geometry with three bidentate ligands and assume a <i>facial</i>-isomer with Δ- and Λ-enantimorphs. Three imidazole groups of <i>fac</i>-[Fe^II(HL^{<i>n</i>‑Pr})₃]²⁺ are hydrogen-bonded to three Cl^– ions. The 3:3 NH­(imidazole)···Cl^– hydrogen-bonds form a stepwise ladder assembly structure, which is maintained during the spin transition process. The spin transition process is related to the structural changes of the FeN₆ coordination environment, the order–disorder of PF₆^– anion, and the conformation change of <i>n</i>-propyl groups. The Fe–N bond distance in the HS state is longer by 0.2 Å than that in the LS state. Disorder of PF₆^– anion is not observed in the LS state but in the HS state. The conformational changes of <i>n</i>-propyl groups are found in the spin transition processes except for HS → HS­(<i>T</i>₁) → HS­(<i>T</i>₂)

Syntheses, Structures, and Magnetic Properties of Acetato- and Diphenolato-Bridged 3d–4f Binuclear Complexes [M(3-MeOsaltn)(MeOH)_<i>x</i>(ac)­Ln(hfac)₂] (M = Zn^II, Cu^II, Ni^II, Co^II; Ln = La^III, Gd^III, Tb^III, Dy^III; 3‑MeOsaltn = <i>N,N</i>′‑Bis(3-methoxy-2-oxybenzylidene)-1,3-propanediaminato; ac = Acetato; hfac = Hexafluoroacetylacetonato; <i>x</i> = 0 or 1)

A series of 3d–4f binuclear complexes, [M­(3-MeOsaltn)­(MeOH)_<i>x</i>(ac)­Ln­(hfac)₂] (<i>x</i> = 0 for M = Cu^II, Zn^II; <i>x</i> = 1 for M = Co^II, Ni^II; Ln = Gd^III, Tb^III, Dy^III, La^III), have been synthesized and characterized, where 3-MeOsaltn, ac, and hfac denote <i>N,N</i>′-bis­(3-methoxy-2-oxybenzylidene)-1,3-propanediaminato, acetato, and hexafluoroacetylacetonato, respectively. The X-ray analyses demonstrated that all the complexes have an acetato- and diphenolato-bridged M^II–Ln^III binuclear structure. The Cu^II–Ln^III and Zn^II–Ln^III complexes are crystallized in an isomorphous triclinic space group <i>P</i>1̅, where the Cu^II or Zn^II ion has square pyramidal coordination geometry with N₂O₂ donor atoms of 3-MeOsaltn at the equatorial coordination sites and one oxygen atom of the bridging acetato ion at the axial site. The Co^II–Ln^III and Ni^II–Ln^III complexes are crystallized in an isomorphous monoclinic space group <i>P</i>2₁/<i>c</i>, where the Co^II or Ni^II ion at the high-spin state has an octahedral coordination environment with N₂O₂ donor atoms of 3-MeOsaltn at the equatorial sites, and one oxygen atom of the bridged acetato and a methanol oxygen atom at the two axial sites. Each Ln^III ion for all the complexes is coordinated by four oxygen atoms of two phenolato and two methoxy oxygen atoms of “ligand-complex” M­(3-MeOsaltn), four oxygen atoms of two hfac^–, and one oxygen atom of the bridging acetato ion; thus, the coordination number is nine. The temperature dependent magnetic susceptibilities from 1.9 to 300 K and the field-dependent magnetization up to 5 T at 1.9 K were measured. Due to the important orbital contributions of the Ln^III (Tb^III, Dy^III) and to a lesser extent the M^II (Ni^II, Co^II) components, the magnetic interaction between M^II and Ln^III ions were investigated by an empirical approach based on a comparison of the magnetic properties of the M^II–Ln^III, Zn^II–Ln^III, and M^II–La^III complexes. The differences of χ_M<i>T</i> and <i>M</i>(<i>H</i>) values for the M^II–Ln^III, Zn^II–Ln^III and those for the M^II–La^III complexes, that is, Δ­(<i>T</i>) = (χ_M<i>T</i>)_MLn – (χ_M<i>T</i>)_ZnLn – (χ_M<i>T</i>)_MLa = <i>J</i>_MLn(<i>T</i>) and Δ­(<i>H</i>) = <i>M</i>_MLn(<i>H</i>) – <i>M</i>_ZnLn(<i>H</i>) – <i>M</i>_MLa(<i>H</i>) = <i>J</i>_MLn(<i>H</i>), give the information of 3d–4f magnetic interaction. The magnetic interactions are ferromagnetic if M^II = (Cu^II, Ni^II, and Co^II) and Ln = (Gd^III, Tb^III, and Dy^III). The magnitudes of the ferromagnetic interaction, <i>J</i>_MLn(<i>T</i>) and <i>J</i>_MLn(<i>H</i>), are in the order Cu^II–Gd^III > Cu^II–Dy^III > Cu^II–Tb^III, while those are in the order of M^II–Gd^III ≈ M^II–Tb^III > M^II–Dy^III for M^II = Ni^II and Co^II. Alternating current (ac) susceptibility measurements demonstrated that the Ni^II–Tb^III and Co^II–Tb^III complexes showed out-of-phase signal with frequency-dependence and the Ni^II–Dy^III and Co^II–Dy^III complexes showed small frequency-dependence. The energy barrier for the spin flipping was estimated from the Arrhenius plot to be 14.9(6) and 17.0(4) K for the Ni^II–Tb^III and Co^II–Tb^III complexes, respectively, under a dc bias field of 1000 Oe

Syntheses, Structures, and Magnetic Properties of Acetato- and Diphenolato-Bridged 3d–4f Binuclear Complexes [M(3-MeOsaltn)(MeOH)_<i>x</i>(ac)­Ln(hfac)₂] (M = Zn^II, Cu^II, Ni^II, Co^II; Ln = La^III, Gd^III, Tb^III, Dy^III; 3‑MeOsaltn = <i>N,N</i>′‑Bis(3-methoxy-2-oxybenzylidene)-1,3-propanediaminato; ac = Acetato; hfac = Hexafluoroacetylacetonato; <i>x</i> = 0 or 1)

A series of 3d–4f binuclear complexes, [M­(3-MeOsaltn)­(MeOH)_<i>x</i>(ac)­Ln­(hfac)₂] (<i>x</i> = 0 for M = Cu^II, Zn^II; <i>x</i> = 1 for M = Co^II, Ni^II; Ln = Gd^III, Tb^III, Dy^III, La^III), have been synthesized and characterized, where 3-MeOsaltn, ac, and hfac denote <i>N,N</i>′-bis­(3-methoxy-2-oxybenzylidene)-1,3-propanediaminato, acetato, and hexafluoroacetylacetonato, respectively. The X-ray analyses demonstrated that all the complexes have an acetato- and diphenolato-bridged M^II–Ln^III binuclear structure. The Cu^II–Ln^III and Zn^II–Ln^III complexes are crystallized in an isomorphous triclinic space group <i>P</i>1̅, where the Cu^II or Zn^II ion has square pyramidal coordination geometry with N₂O₂ donor atoms of 3-MeOsaltn at the equatorial coordination sites and one oxygen atom of the bridging acetato ion at the axial site. The Co^II–Ln^III and Ni^II–Ln^III complexes are crystallized in an isomorphous monoclinic space group <i>P</i>2₁/<i>c</i>, where the Co^II or Ni^II ion at the high-spin state has an octahedral coordination environment with N₂O₂ donor atoms of 3-MeOsaltn at the equatorial sites, and one oxygen atom of the bridged acetato and a methanol oxygen atom at the two axial sites. Each Ln^III ion for all the complexes is coordinated by four oxygen atoms of two phenolato and two methoxy oxygen atoms of “ligand-complex” M­(3-MeOsaltn), four oxygen atoms of two hfac^–, and one oxygen atom of the bridging acetato ion; thus, the coordination number is nine. The temperature dependent magnetic susceptibilities from 1.9 to 300 K and the field-dependent magnetization up to 5 T at 1.9 K were measured. Due to the important orbital contributions of the Ln^III (Tb^III, Dy^III) and to a lesser extent the M^II (Ni^II, Co^II) components, the magnetic interaction between M^II and Ln^III ions were investigated by an empirical approach based on a comparison of the magnetic properties of the M^II–Ln^III, Zn^II–Ln^III, and M^II–La^III complexes. The differences of χ_M<i>T</i> and <i>M</i>(<i>H</i>) values for the M^II–Ln^III, Zn^II–Ln^III and those for the M^II–La^III complexes, that is, Δ­(<i>T</i>) = (χ_M<i>T</i>)_MLn – (χ_M<i>T</i>)_ZnLn – (χ_M<i>T</i>)_MLa = <i>J</i>_MLn(<i>T</i>) and Δ­(<i>H</i>) = <i>M</i>_MLn(<i>H</i>) – <i>M</i>_ZnLn(<i>H</i>) – <i>M</i>_MLa(<i>H</i>) = <i>J</i>_MLn(<i>H</i>), give the information of 3d–4f magnetic interaction. The magnetic interactions are ferromagnetic if M^II = (Cu^II, Ni^II, and Co^II) and Ln = (Gd^III, Tb^III, and Dy^III). The magnitudes of the ferromagnetic interaction, <i>J</i>_MLn(<i>T</i>) and <i>J</i>_MLn(<i>H</i>), are in the order Cu^II–Gd^III > Cu^II–Dy^III > Cu^II–Tb^III, while those are in the order of M^II–Gd^III ≈ M^II–Tb^III > M^II–Dy^III for M^II = Ni^II and Co^II. Alternating current (ac) susceptibility measurements demonstrated that the Ni^II–Tb^III and Co^II–Tb^III complexes showed out-of-phase signal with frequency-dependence and the Ni^II–Dy^III and Co^II–Dy^III complexes showed small frequency-dependence. The energy barrier for the spin flipping was estimated from the Arrhenius plot to be 14.9(6) and 17.0(4) K for the Ni^II–Tb^III and Co^II–Tb^III complexes, respectively, under a dc bias field of 1000 Oe