Halogen-Bonded Supramolecular Parallelograms: From Self-Complementary Iodoalkyne Halogen-Bonded Dimers to 1:1 and 2:2 Iodoalkyne Halogen-Bonded Cocrystals

The formation of supramolecular parallelograms utilizing iodoalkyne-pyridine halogen bonding is described. The crystal structures of four iodoalkynyl-substituted (phenylethynyl)pyridines demonstrate the feasibility of discrete self-complementary dimer formation. These compounds 3-(2-iodoethynyl-phenylethynyl) pyridine (1), 2-(3-iodoethynyl-phenylethynyl) pyridine (2), 3-(4,5-difluoro-2-iodoethynyl-phenylethynyl) pyridine (3), and 2-(5-iodoethynyl-2,4-dimethylphenylethynyl) pyridine (4) all form parallelogram-shaped dimers with two self-complementary short N-I halogen bonds. The potential formation of iodoalkynyl halogen-bonded supramolecular macrocycles is demonstrated by the formation of a discrete halogen-bonded parallelogram-shaped complex in the 1:1 cocrystal formed from the bis iodoalkyne, 1-iodoethynyl-2-(3-iodoethynyl-phenylethynyl)-4,5-dimethoxybenzene (6), and the dipyridyl, 5-phenyl-2-(pyridin-3-ylethynyl)pyridine (7). Furthermore, discrete supramolecular parallelograms form within the 2:2 cocrystal formed between 1,2-bis(iodoethynyl)-4,5-difluorobenzene and the dipyridyl 4-(3-pyridylethynyl) pyridine (8).

Evidence-based guideline: unexplained infertility†

STUDY QUESTION

What is the recommended management for couples presenting with unexplained infertility (UI), based on the best available evidence in the literature?

SUMMARY ANSWER

The evidence-based guideline on UI makes 52 recommendations on the definition, diagnosis, and treatment of UI.

WHAT IS KNOWN ALREADY

UI is diagnosed in the absence of any abnormalities of the female and male reproductive systems after 'standard' investigations. However, a consensual standardization of the diagnostic work-up is still lacking. The management of UI is traditionally empirical. The efficacy, safety, costs, and risks of treatment options have not been subjected to robust evaluation.

STUDY DESIGN, SIZE, DURATION

The guideline was developed according to the structured methodology for ESHRE guidelines. Following formulation of key questions by a group of experts, literature searches, and assessments were undertaken. Papers written in English and published up to 24 October 2022 were evaluated.

PARTICIPANTS/MATERIALS, SETTING, METHODS

Based on the available evidence, recommendations were formulated and discussed until consensus was reached within the guideline development group (GDG). Following stakeholder review of an initial draft, the final version was approved by the GDG and the ESHRE Executive Committee.

MAIN RESULTS AND THE ROLE OF CHANCE

This guideline aims to help clinicians provide the best care for couples with UI. As UI is a diagnosis of exclusion, the guideline outlined the basic diagnostic procedures that couples should/could undergo during an infertility work-up, and explored the need for additional tests. The first-line treatment for couples with UI was deemed to be IUI in combination with ovarian stimulation. The place of additional and alternative options for treatment of UI was also evaluated. The GDG made 52 recommendations on diagnosis and treatment for couples with UI. The GDG formulated 40 evidence-based recommendations-of which 29 were formulated as strong recommendations and 11 as weak-10 good practice points and two research only recommendations. Of the evidence-based recommendations, none were supported by high-quality evidence, one by moderate-quality evidence, nine by low-quality evidence, and 31 by very low-quality evidence. To support future research in UI, a list of research recommendations was provided.

LIMITATIONS, REASONS FOR CAUTION

Most additional diagnostic tests and interventions in couples with UI have not been subjected to robust evaluation. For a large proportion of these tests and treatments, evidence was very limited and of very low quality. More evidence is required, and the results of future studies may result in the current recommendations being revised.

WIDER IMPLICATIONS OF THE FINDINGS

The guideline provides clinicians with clear advice on best practice in the care of couples with UI, based on the best evidence currently available. In addition, a list of research recommendations is provided to stimulate further studies in the field. The full guideline and a patient leaflet are available in www.eshre.eu/guideline/UI.

STUDY FUNDING/COMPETING INTEREST(S)

The guideline was developed by ESHRE, who funded the guideline meetings, literature searches, and dissemination of the guideline in collaboration with the Monash University led Australian NHMRC Centre of Research Excellence in Women's Health in Reproductive Life (CREWHIRL). The guideline group members did not receive any financial incentives; all work was provided voluntarily. D.R. reports honoraria from IBSA and Novo Nordisk. B.A. reports speakers' fees from Merck, Gedeon Richter, Organon and Intas Pharma; is part of the advisory board for Organon Turkey and president of the Turkish Society of Reproductive Medicine. S.B. reports speakers' fees from Merck, Organon, Ferring, the Ostetric and Gynaecological Society of Singapore and the Taiwanese Society for Reproductive Medicine; editor and contributing author, Reproductive Medicine for the MRCOG, Cambridge University Press; is part of the METAFOR and CAPE trials data monitoring committee. E.B. reports research grants from Roche diagnostics, Gedeon Richter and IBSA; speaker's fees from Merck, Ferring, MSD, Roche Diagnostics, Gedeon Richter, IBSA; E.B. is also a part of an Advisory Board of Ferring Pharmaceuticals, MSD, Roche Diagnostics, IBSA, Merck, Abbott and Gedeon Richter. M.M. reports consulting fees from Mojo Fertility Ltd. R.J.N. reports research grant from Australian National Health and Medical Research Council (NHMRC); consulting fees from Flinders Fertility Adelaide, VinMec Hospital Hanoi Vietnam; speaker's fees from Merck Australia, Cadilla Pharma India, Ferring Australia; chair clinical advisory committee Westmead Fertility and research institute MyDuc Hospital Vietnam. T.P. is a part of the Research Council of Finland and reports research grants from Roche Diagnostics, Novo Nordics and Sigrid Juselius foundation; consulting fees from Roche Diagnostics and organon; speaker's fees from Gedeon Richter, Roche, Exeltis, Organon, Ferring and Korento patient organization; is a part of NFOG, AE-PCOS society and several Finnish associations. S.S.R. reports research grants from Roche Diagnostics, Organon, Theramex; consulting fees from Ferring Pharmaceuticals, MSD and Organon; speaker's fees from Ferring Pharmaceuticals, MSD/Organon, Besins, Theramex, Gedeon Richter; travel support from Gedeon Richter; S.S.R. is part of the Data Safety Monitoring Board of TTRANSPORT and deputy of the ESHRE Special Interest Group on Safety and Quality in ART; stock or stock options from IVI Lisboa, Clínica de Reprodução assistida Lda; equipment/medical writing/gifts from Roche Diagnostics and Ferring Pharmaceuticals. S.K.S. reports speakers' fees from Merck, Ferring, MSD, Pharmasure. HRV reports consulting and travel fees from Ferring Pharmaceuticals. The other authors have nothing to disclose.

DISCLAIMER

This guideline represents the views of ESHRE, which were achieved after careful consideration of the scientific evidence available at the time of preparation. In the absence of scientific evidence on certain aspects, a consensus between the relevant ESHRE stakeholders has been obtained. Adherence to these clinical practice guidelines does not guarantee a successful or specific outcome, nor does it establish a standard of care. Clinical practice guidelines do not replace the need for application of clinical judgment to each individual presentation, nor variations based on locality and facility type. ESHRE makes no warranty, express or implied, regarding the clinical practice guidelines and specifically excludes any warranties of merchantability and fitness for a particular use or purpose. (Full disclaimer available at www.eshre.eu/guidelines.).

Co-crystal sustained by π-type halogen-bonding inter-actions between 1,4-di-iodo-perchloro-benzene and naphthalene

The formation and crystal structure of a co-crystal based upon 1,4-di-iodo-perchloro-benzene (C6I2Cl4) as the halogen-bond donor along with naphthalene (nap) as the acceptor is reported. The co-crystal [systematic name: 1,2,4,5-tetra-chloro-3,6-di-iodo-benzene-naphthalene, (C6I2Cl4)·(nap)] generates a chevron-like structure that is held together primarily by π-type halogen bonds (i.e. C-I⋯π contacts) between the components. In addition, C6I2Cl4 also inter-acts with the acceptor via C-Cl⋯π contacts that help stabilize the co-crystal. Within the solid, both aromatic components are found to engage in offset and homogeneous face-to-face π-π stacking inter-actions. Lastly, the halogen-bond donor C6I2Cl4 is found to engage with neighboring donors by both Type I chlorine-chlorine and Type II iodine-chlorine contacts, which generates an extended structure.

Rapid Access to Encapsulated Molecular Rotors via Coordination-Driven Macrocycle Formation

Macrocycle formation that relies upon trans metal coordination of appropriately placed pyridine ligands within an arylene ethynylene construct provides rapid and reliable access to molecular rotators encapsulated within macrocyclic stators. Showing no significant close contacts to the central rotators, X-ray crystallography of AgI -coordinated macrocycles provides plausibility for unobstructed rotation or wobbling of rotators within the central cavity. Solid-state 13 C NMR of PdII -coordinated macrocycles supports the notion of unobstructed movement of simple arenes in the crystal lattice. Solution 1 H NMR studies indicate complete and immediate macrocycle formation upon the introduction of PdII to the pyridyl-based ligand at room temperature. Moreover, the formed macrocycle is stable in solution; a lack of significant changes in the 1 H NMR spectrum upon cooling to -50 °C is consistent with the absence of dynamic behavior. The synthetic route to these macrocycles is expedient and modular, providing access to rather complex constructs in four simple steps involving Sonogashira coupling and deprotection reactions.

π-Complexation and C-H hydrogen bonding in the formation of colored cocrystals

The present study evaluates the potential combination of charge-transfer electron-donor-acceptor π-π complexation and C-H hydrogen bonding to form colored cocrystals. The crystal structures of the red 1:1 cocrystals formed from the isomeric pyridines 4- and 3-{2-[4-(dimethylamino)phenyl]ethynyl}pyridine with 1-[2-(3,5-dinitrophenyl)ethynyl]-2,3,5,6-tetrafluorobenzene, both C₁₄H₄F₄N₂O₄·C₁₅H₁₄N₂, are reported. Intermolecular interaction energy calculations confirm that π-stacking interactions dominate the intermolecular interactions within each crystal structure. The close contacts revealed by Hirshfeld surface calculations are predominantly C-H interactions with N, O, and F atoms.

Halogen-bonded co-crystal containing 1,3-di-iodo-perchloro-benzene and the photoproduct rtct-tetra-kis-(pyridin-4-yl)cyclo-butane resulting in a zigzag topology

The formation and crystal structure of a zigzag network held together by I⋯N halogen bonds is reported. In particular, the halogen-bond donor is 1,3-di-iodo-perchloro-benzene (C₆I₂Cl₄ ) while the acceptor is the photoproduct rtct-tetra-kis-(pyridin-4-yl)cyclo-butane (TPCB). Curiously, within the resulting co-crystal (C₆I₂Cl₄ )·(TPCB), the photoproduct accepts only two halogen bonds between neighbouring 4-pyridyl rings and as a result behaves as a bent two-connected node rather than the expected four-connected centre. In addition, the photoproduct, TPCB, is also found to engage in C-H⋯N hydrogen bonds, forming an extended zigzag chain.

A structural and computational comparison of close contacts and related intermolecular energies of interaction in the structures of 1,3-diiodo-5-nitrobenzene, 1,3-dibromo-5-nitrobenzene, and 1,3-dichloro-5-nitrobenzene

1,3-Diiodo-5-nitrobenzene, C6H3I2NO2, and 1,3-dibromo-5-nitrobenzene, C6H3Br2NO2, crystallize in the centrosymmetric space group P21/m, and are isostructural with 1,3-dichloro-5-nitrobenzene, C6H3Cl2NO2, that has been redetermined at 100 K for consistency. While the three-dimensional packing in all three structures is similar, the size of the halogen atom affects the nonbonded close contacts observed between molecules. Thus, the structure of 1,3-diiodo-5-nitrobenzene features a close Type 1 I...I contact, the structure of 1,3-dibromo-5-nitrobenzene features a self-complementary nitro-O...Br close contact, while the structure of 1,3-dichloro-5-nitrobenzene also has a self-complementary nitro-O...Cl interaction, as well as a bifurcated C—H...O(nitro) close contact. Notably, the major energetically attractive intermolecular interaction between adjacent molecules in each of the three structures corresponds to a π-stacked interaction. The self-complementary halogen...O(nitro) and C—H...O(nitro) interactions correspond to significant cohesive attraction between molecules in each structure, while the Type 1 halogen–halogen contact is weakly cohesive.

Co-operative halogen bonds and nonconventional sp-C-H...O hydrogen bonds in 1:1 cocrystals formed between diethynylpyridines and N-halosuccinimides

The rapid evaporation of 1:1 solutions of diethynylpyridines and N-halosuccinimides, that react together to form haloalkynes, led to the isolation of unreacted 1:1 cocrystals of the two components. The 1:1 cocrystal formed between 2,6-diethynylpyridine and N-iodosuccinimide (C₄H₄INO₂·C₉H₅N) contains an N-iodosuccinimide-pyridine I...N halogen bond and two terminal alkyne-succinimide carbonyl C-H...O hydrogen bonds. The three-dimensional extended structure features interwoven double-stranded supramolecular polymers that are interconnected through halogen bonds. The cocrystal formed between 3,5-diethynylpyridine and N-iodosuccinimide (C₄H₄INO₂·C₉H₅N) also features an I...N halogen bond and two C-H...O hydrogen bonds. However, the components form essentially planar double-stranded one-dimensional zigzag supramolecular polymers. The cocrystal formed between 3,5-diethynylpyridine and N-bromosuccinimide (C₄H₄BrNO₂·C₉H₅N) is isomorphous to the cocrystal formed between 3,5-diethynylpyridine and N-iodosuccinimide, with a Br...N halogen bond instead of an I...N halogen bond.

P-386 Serum P levels measured on the day of embryo transfer in FET modified natural cycles are not related to pregnancy outcome

Study question

Is there an optimal serum progesterone (P) threshold in frozen embryo transfer (FET) modified natural cycles when luteal phase support (LPS) is given?

Summary answer

Serum P measured on the day of ET is not related with ongoing pregnancy outcome when doing a modified natural cycle with LPS.

What is known already

Recent publications showed that there is a minimum threshold of serum P that needs to be reached in artificial cycles to optimize pregnancy rates. When using micronized vaginal P (MVP), about 30% of patients show low levels of serum P (<9 ng/mL) leading to a significant decrease in ongoing pregnancy; although this situation can be reverted by increasing and modifying the route of exogenous P. In pure natural cycles without LPS, serum P below 10 ng/mL impairs pregnancy outcome. Nevertheless, there is no data about the impact of serum P levels in modified natural cycles in which LPS is given.

Study design, size, duration

Prospective cohort unicentric study performed in IVI RMA Valencia (Spain), including 244 cycles from February 2020 to January 2021.

Participants/materials, setting, methods

Infertile patients <50 y.o. and BMI<40Kg/m2 undergoing a FET of a maximum of 2 blastocysts, from own or donated oocytes. FET were performed in the context of a modified natural cycle (single injection of rec-hCG when dominant follicle reached 17mm and endometrial thickness >6.5mm). MVP was used for LPS (200mg/12h). Ongoing pregnancy rate (OPR) was correlated with serum P levels on the FET day, measured within two hours before transfer.

Main results and the role of chance

A total of 241 patients were analyzed. Mean age was 38.1 + 3.8 years, with a mean BMI of 23.3 + 3.9. On the rec-hCG day the mean leading follicle size was 17.7±0.1 mm. The endometrium displayed a trilaminar pattern, with a mean thickness of 7.8±3.3 mm, and mean P and estradiol (E2) levels were 0.30±0.03 ng/ml and 249.39±11.03  pg/ml, respectively. A mean of 1.1 blastocysts were transferred (90.9% were single embryo transfers), 27.4% (66) from donated and 72.6 % (175) from own oocytes. On the day of FET, the mean serum P and E2 levels were 26.19 + 8.97ng/mL and 154.12 + 96.08pg/mL, respectively. The overall OPR was 51.5% (124). OPR according to quartiles of serum P (ng/mL) was 56.7% (Q1, P < 20.2), 47.5% (Q2, P > 20.2-24.8), 51.7% (Q3, P > 24.8-31.1), 50.0% (Q4, P > 31.1), p = 0.78). Multivariate logistic regression showed that serum P was not related with OPR after adjusting for age, BMI, E2 and origin of oocytes (aOR:0.98, 95% CI:0.93-1.04, p = 0.47). Only 2 patients had serum P levels below 10 ng/mL, with values of 8.6 and 8.8 ng/mL on the ET day and had a negative pregnancy test.

Limitations, reasons for caution

As part of our routine clinical practice, MVP (200mg/12h) is given for LPS in patients undergoing a FET in the context of a modified natural cycle. Thus, these results cannot be extrapolated to LPS-free or any other LPS protocol in FET modified natural cycles.

Wider implications of the findings

The majority of patients undergoing FET in modified natural cycles when using LPS have adequate levels of serum P and thus, do not have an impact on pregnancy outcome. According to our data, there is no need to measure serum P levels on the luteal phase of modified natural cycles.

Trial registration number

NCT04259996

P-601 Is Medroxiprogesterone acetate (MPA) an adequate alternative to GnRH antagonist in oocyte vitrification for non oncological fertility preservation (FP) and preimplantation genetic test (PGT-A) cycles?

Study question

Can we use MPA as a pituitary inhibitor instead of the GnRH antagonist in ovarian stimulation protocols in non-oncological fertility preservation and PGT-A cycles?

Summary answer

MPA can act as a substitute of GnRH antagonist for pituitary suppression in FP and PGT-A cycles, since the results are similar between both groups.

What is known already

Progestin-primed ovarian stimulation (PPOS) protocols using exogenous progesterone to replace GnRH analogs during the follicular phase of OS have emerged as an efficient alternative to prevent LH from peaking and have been used successfully in different types of patients.

Fertility preservation (FP) and preimplantation genetic testing (PGT-A) have become new emerging areas of assisted reproduction. FP gives women the ability to have children using their own gametes after age-related fertility decline, while PGT-A appears to improve reproductive outcomes in advanced maternal age at increased risk of aneuploid embryos. However, few data are available for both indications regarding PPOS cycle outcomes.

Study design, size, duration

Multicenter, retrospective, observational, cohort study conducted in eleven IVIRMA centers attached to private universities.

We included a total of 4,961 cycles of non-oncological fertility preservation that were distributed as follows: n = 494 were stimulated under a PPOS protocol while n = 4,467 received a GnRH antagonist. Regarding PGT-A cycles, we analyzed 12,461 treatments, of which n = 686 and n = 11,775 received MPA and GnRH antagonist, respectively. Cycles were performed from January 2017 to December 2021.

Participants/materials, setting, methods

Patients were divided according to the protocol used for preventing premature luteinization during follicular phase of OS. In the MPA group, participants received 10 mg daily administered orally, while in the control group, women received an antagonist once the main follicle reached 13 mm.

In FP cycles, ovarian response specific parameters were evaluated, such as endocrine profile and mature oocytes; in PGT-A treatments, main variables were number of biopsied and aneuploid embryos and reproductive outcomes.

Main results and the role of chance

Regarding FP's baseline characteristics, age was statistically but not clinically significant between the two groups. Length of ovarian stimulation and total dose of hMG administered were similar in both groups, despite the significantly higher total dose of FSH administered in MPA compared to the GnRH antagonist group (p = 0.008) . Number of mature oocytes retrieved (10.2 [95% CI 9.6-10.8] vs 9 [95% CI 8.8-9.2]) was significantly higher in MPA compared to antagonist group; this trend continued regardless of age (≤ 35 or > 35 years).

PGT-A cycles followed the same tendency in terms of demographic characteristics. Length of OS was comparable between groups, whilst the total dose of rFSH and hp-HMG administered in the MPA were significantly higher than that in the GnRH antagonist group. Although the number of MII was comparable and despite the lower number of embryos biopsied in the MPA group (4.5±0.2 vs 4.7±0.06, p = 0.031) the number of aneuploid embryos was similar between the two groups (2.3±0.1 vs 2.4±0.04, p = 0.474), as well as implantation (56% vs. 54% p = 0.359) and clinical pregnancy rate (64.1% vs. 62.1, p = 0.316). The miscarriage rate was significantly lower in the group treated with MPA compared to GnRH antagonists (4.7% vs. 8.2%, p = 0.001).

Limitations, reasons for caution

The retrospective nature of this study may be a reason for caution and only association, not causation, can be inferred from the results. Despite being the largest sample size ever reported with PPOS in no oncological FP and PGT-A, the number of patients included is still low.

Wider implications of the findings

The administration of PPOS yielded similar or even better results than those observed with GnRH antagonists in terms of oocytes retrieved, rate of aneuploid embryos or clinical results. Therefore, PPOS could be recommended for ovarian stimulation in non-oncological FP and PGT-A cycles as it allows for a more patient-friendly approach.

Trial registration number

Not applicable

P-650 Partial premature ovulation detection during follicular aspiration compromises the quantity but not the quality of the retrieved oocytes in stimulated fresh IVF cycles

Study question

Is partial premature ovulation (PPO) detection during the oocyte pick-up (OPU) a sign of poor prognosis in in vitro fertilization (IVF) cycles with own oocytes?

Summary answer

PPO halves the number of metaphase II oocytes available for an IVF treatment without reducing their quality, demonstrated by unaltered fertilization and top-quality blastocyst rates.

What is known already

PPO detected during the OPU procedure has not been extensively studied in the literature. This phenomenon may result in a reduction in the number and/or competence of the oocytes retrieved, due to the potential loss of the already expelled oocytes, as well as the likely dominance exerted by the ruptured follicle/s in the rest of the cohort. Despite this, several authors have demonstrated that competent oocytes can be retrieved from these already ruptured follicles, suggesting that oocyte extrusion frequently does not occur after follicle rupture. The potential negative effect exerted in the rest of sibling oocytes remains unknown.

Study design, size, duration

Retrospective cohort analysis performed in IVIRMA Valencia (Spain), including 8994 cycles of controlled ovarian stimulation (COS) for an IVF treatment with fresh own oocytes, between January 2016 and May 2021. OPU procedures for oocyte cryopreservation, as well as mixed cycles with both fresh and frozen oocytes, were discarded. PPO diagnosis was based on ultrasound visualization of any already formed corpus luteum structure/s, a lower follicular count than expected, and/or free fluid.

Participants/materials, setting, methods

Female patients undergoing OPU after COS for a fresh IVF treatment. Cycles in which PPO has been detected will be compared with a random, and of the same size, sample without PPO. Mean number of oocytes, metaphase II, fertilized oocytes and top-quality embryos, as well as IVF success rates, will be compared between both groups. Patients’ basal characteristics and COS parameters will be analyzed in order to detect any potential early indicator of PPO.

Main results and the role of chance

PPO was detected in 123 of the 8994 cycles (1.37%) performed. A random control group of 123 cycles without PPO was selected. Patients’ mean age was 37.6±3.6, with a BMI of 23.3±4.1 kg/m2 and an anti-mullerian hormone of 1.62±1.3 ng/mL. Patient’s basal characteristics and COS parameters were statistically comparable among groups (p > 0.05), except for lower serum estradiol levels (2037.64 vs. 1582.24 pg/mL; p = 0.004) in the PPO group on the last ultrasound prior to OPU. Patients with PPO showed lower aspiration rates (88.95% vs. 55.78% in the PPO gr.), as well as a reduced mean number of oocytes (10.69 vs. 5.68 in the PPO gr.), metaphase II (8.41 vs. 4.33 in the PPO gr.), fertilized oocytes (6.23 vs. 3.26 in the PPO gr.) and top-quality blastocysts (2.77 vs. 1.35 in the PPO gr.) (p = 0.000). In contrast, maturation (80.72% vs. 76.57% in the PPO gr.), fertilization (73.52% vs. 75.18% in the PPO gr.) and top-quality blastocyst rates (44.03% vs. 38.68% in the PPO gr.) were statistically similar between both groups (p > 0.05).

Limitations, reasons for caution

The main limitations of the present study are its retrospective design and its small sample size, derived from the low frequency of the PPO phenomenon in our clinic. Larger prospective studies should be proposed in order to accurately define the negative impact of PPO in IVF success rates.

Wider implications of the findings

PPO clearly reduces the number of oocytes available for an IVF treatment, although it does not seem to impair the competence of the remaining cohort. Once PPO is detected, cycle cancellation may not be worth the associated loss of money, time and morale, especially given its low prevalence (around 1%).

Trial registration number

Not applicable

O-013 The individualised dosing algorithm of follitropin delta, developed in a GnRH antagonist protocol, shows to be highly effective in a long GnRH agonist protocol

Study question

Is the individualised follitropin delta regimen based on serum anti-Müllerian hormone (AMH) concentration and body weight effective and safe in a long GnRH agonist protocol?

Summary answer

Per started stimulation, the live birth rate following fresh transfer was 43% and the cumulative live birth rate following fresh and frozen transfers was 58%.

What is known already

Individualised follitropin delta treatment in a GnRH antagonist protocol reduces the incidence of OHSS and/or preventive interventions without compromising live birth rates. In a multinational, double-blind, randomised trial (RAINBOW, NCT03564509) exploring the efficacy and safety of choriogonadotropin beta in women undergoing ovarian stimulation in a long GnRH agonist protocol, the control group was treated with the same individualised follitropin delta regimen based on AMH (Elecsys AMH Plus Immunoassay) and body weight. Women had one stimulation cycle and were followed up to live birth following the fresh and all frozen blastocyst transfers performed within one year after start of stimulation.

Study design, size, duration

Analysis of fresh and cumulative live birth rates in 104 women (30–42 years, AMH 5-35 pmol/L) down-regulated with 0.1 mg/day triptorelin and stimulated in one cycle with a fixed individualised daily dose of follitropin delta. Triggering was performed when 3 follicles ≥17 mm. Oocytes were inseminated by ICSI; blastocyst transfer was on day 5 and remaining blastocysts were cryopreserved on day 5/6 and subsequently used for frozen transfers.

Participants/materials, setting, methods

Data collection included live birth and neonatal health follow-up for all transfers of fresh or frozen embryos performed within one year after the start of stimulation. The data presented are based on all women who were down-regulated and started stimulation. The cumulative live birth rate was calculated as the percentage of women starting stimulation that had at least one live born neonate.

Main results and the role of chance

Of 104 women starting stimulation, 101 had triggering. Two subjects were cancelled due to poor response and one due to adverse event. Nine subjects had transfer cancellations; six due to no day 5 blastocyst available, and one each due to risk of OHSS, adverse event, and other reason. The average daily dose of follitropin delta was 11.0±1.6 and the duration of stimulation was 10.3±1.6 days. The mean number of oocytes was 12.5±6.4; the mean number of blastocysts was 5.1±3.4; and 85% had at least one good-quality blastocyst. Following mostly single blastocyst transfer (95%), the ongoing pregnancy rate (10–11 weeks after transfer) was 43% per started stimulation. There were six cases of early OHSS (5.8%) graded as mild (3) and moderate (3) and six cases with late OHSS (5.8%) graded as moderate (3) and severe (3).

In total, 92% of women had at least one fresh or frozen transfer and 150 blastocyst transfers were performed (92 fresh and 58 frozen transfers). Per started stimulation, the live-birth rate following fresh transfer was 43% and the cumulative live-birth rate following fresh and all frozen transfers was 58%. There were three neonates with congenital anomalies following fresh transfer and none following frozen transfer.

Limitations, reasons for caution

This is the first clinical trial investigating the individualised follitropin delta regimen in a long GnRH agonist protocol. A final evaluation of this regimen requires comparative data. Accordingly, a randomised trial comparing follitropin delta in a long GnRH agonist protocol vs. in a GnRH antagonist protocol is currently ongoing (NCT03809429).

Wider implications of the findings

The use of individualised follitropin delta dosing based on AMH and body weight in a long GnRH agonist protocol resulted in high fresh and cumulative live birth rates, and with an incidence of OHSS similar to previously reported for other FSH products in long GnRH agonist protocols.

Trial registration number

NCT03564509

Controlling Thermal Expansion in Supramolecular Halogen-Bonded Mixed Cocrystals through Synthetic Feed and Dynamic Motion

Control over thermal expansion (TE) behaviors in solid materials is often accomplished by modifying the molecules or intermolecular interactions within the solid. Here, we use a mixed cocrystal approach and incorporate molecules with similar chemical structures, but distinct functionalities. Development of mixed cocrystals is at a nascent stage, and here we describe the first mixed cocrystals sustained by one-dimensional halogen bonds. Within each mixed cocrystal, the halogen-bond donor is fixed, while the halogen-bond acceptor site contains two molecules in a variable ratio. X-ray diffraction demonstrates isostructurality across the series, and SEM-EDS shows equal distribution of heavy atoms and similar atomic compositions across all mixed cocrystals. The acceptor molecules differ in their ability to undergo dynamic motion in the solid state. The synthetic equivalents of motion capable and incapable molecules were systematically varied to yield direct tunabililty in TE behavior.

Halogen-bonded zigzag molecular network based upon 1,2-diiodoperchlorobenzene and the photoproduct rctt-1,3-bis(pyridin-4-yl)-2,4-diphenylcyclobutane

The formation of a halogen-bonded zigzag mol­ecular network based upon 1,2-di­iodo­perchloro­benzene and the head-to-tail photoproduct rctt −1,3-bis­(pyridin-4-yl)-2,4-di­phenyl­cyclo­butane is reported. The co-crystal is sustained by I⋯N halogen bonds where the photoproduct acts as a linear linker while the donor behaves as a bent two-connected node within the zigzag chain.

The formation and crystal structure of a zigzag mol­ecular network held together by I⋯N halogen bonds is reported. In particular, the halogen-bond donor is 1,2-di­iodo­perchloro­benzene (1,2-C₆I₂Cl₄) while the acceptor is a head-to-tail photoproduct, namely rctt-1,3-bis­(pyridin-4-yl)-2,4-di­phenyl­cyclo­butane (ht-PP). In this co-crystal (1,2-C₆I₂Cl₄)·(ht-PP), the donor acts as a bent two-connected node while the acceptor behaves as a linear linker to form the extended solid. Neighbouring chains pack in a tongue-and-groove-like pattern that engage in various Cl⋯π inter­actions to both the phenyl and pyridyl rings resulting in a supra­molecular two-dimensional sheet.

5-{[4-(Dimethylamino)phenyl]ethynyl}pyrimidine–1,2,3,5-tetrafluoro-4,6-diiodobenzene (1/2)

The treatment of 5-{[4-(dimethylamino)phenyl]ethynyl}pyrimidine with a threefold excess of 1,2,3,5-tetrafluoro-4,6-diiodobenzene in dichloromethane solution led to the formation of the unexpected 1:2 title co-crystal, C14H13N3·2CF4I2. In the extended structure, two unique C—I...N halogen bonds from one of the 1,2,3,5-tetrafluoro-4,6-diiodobenzene molecules to the pyrimidine N atoms of the 5-{[4-(dimethylamino)phenyl]ethynyl}pyrimidine molecule generate [110] chains and layers of these chains are π-stacked along the a-axis direction. The second 1,2,3,5-tetrafluoro-4,6-diiodobenzene molecule resides in channels formed parallel to the a-axis direction between stacks of 5-{[4-(dimethylamino)phenyl]ethynyl}pyrimidine molecules and interacts with them via C—I...π(alkyne) contacts.

Cooperative non-covalent interactions and synthetic feed as driving forces to structural diversity within organic co-crystals containing isosteric perhalobenzenes

The formation of three co-crystals based upon a pair of isosteric halogen-bond donors, namely 1,4-diiodoperchlorobenzene and 1,4-diiodoperfluorobenzene, along with the acceptor trans-1-(4-methylbenzoate)-2-(4-pyridyl)ethylene is reported. Along with the varied stoichiometric ratios...

NOS3 rs1799983 and rs2070744 polymorphisms and their association with advanced chronic kidney disease and coronary heart disease in Canarian population with type 2 diabetes

CONTEXT

Different polymorphisms of the endothelial nitric oxide synthase gene (NOS3) have been related to diabetic kidney disease.

OBJECTIVE

To evaluate the association between advanced diabetic chronic kidney disease (ACKD) and the rs1799983 and rs2070744 poymorphisms of NOS3 in a population from the Gran Canaria island.

DESIGN

Cross-sectional case-control study.

SUBJECTS AND METHODS

Polymorphisms were genotyped in 152 subjects with ACKD secondary to type 2 diabetes [estimated glomerular filtration rate (eGFR) <30 mL/min/1.73 m²], 110 subjects with type 2 diabetes for 20 or more years since diagnosis without ACKD (eGFR ≥45 mL/min/1.73m² and albumin/creatinine ratio <300 mg/g and/or 24-h urinary albumin excretion <300 mg) and 292 healthy controls. Association between both polymorphisms and established coronary heart disease (CHD) was also analyzed in both groups with diabetes.

RESULTS

A greater proportion of homozygous individuals for the risk allele C of rs2070744 was found among subjects with ACKD. Association between ACKD and rs2070744 was observed in a recessive genetic model, both for comparison to subjects with diabetes but no ACKD [OR 2.17 (95% CI: 1.17-4.00), p=0.014] and for comparison to healthy controls [OR 1.61 (1.03-2.52), p=0.036]. The frequency of the C allele was significantly higher among subjects with CHD, but only in the group with ACKD. No associations were found for rs1799983.

CONCLUSIONS

NOS3 rs2070744 is associated with ACKD in population with type 2 diabetes from Gran Canaria. A link between this genetic variant and CHD in Canarian subjects with type 2 diabetes could be restricted to cases with ACKD.

Analysis of serum and endometrial progesterone in determining endometrial receptivity

STUDY QUESTION

Is there a relationship between serum and endometrial progesterone (P4) levels, including P4 and metabolites (oestrone, oestradiol and 17α-hydroxyprogesterone), and endometrial receptivity?

SUMMARY ANSWER

Serum P4 levels were not correlated with endometrial P4, nor associated with endometrial receptivity as determined by the ERA® test; however, endometrial P4 and 17α-hydroxyprogesterone levels were positively correlated and related to endometrial receptivity by ERA.

WHAT IS KNOWN ALREADY

Acquisition of endometrial receptivity is governed by P4, which induces secretory transformation. A close relationship between serum P4 and pregnancy outcome is reported for hormone replacement therapy (HRT) cycles. However, the relationship between serum and uterine P4 levels has not been described, and it is unknown whether uterine receptivity depends more on serum or uterine P4 levels.

STUDY DESIGN, SIZE, DURATION

A prospective cohort study was performed during March 2018-2019 in 85 IVF patients undergoing an evaluation-only HRT cycle with oestradiol valerate (6 mg/day) and micronised vaginal progesterone (400 mg/12 h).

PARTICIPANTS/MATERIALS, SETTING, METHODS

Patients were under 50 years of age, had undergone at least one failed IVF cycle, had no uterine pathology, and had adequate endometrial thickness (> 6.5 mm). The study was conducted at IVI Valencia and IVI Foundation. An endometrial biopsy and a blood sample were collected after 5 days of P4 vaginal treatment. Measures included serum P4 levels, ERA®-based evaluation of endometrial receptivity, and endometrial P4 levels along with metabolites (oestrone, oestradiol and 17α-hydroxyprogesterone) measured by ultra-performance liquid chromatography-tandem mass spectrometry.

MAIN RESULTS AND THE ROLE OF CHANCE

Seventy-nine women were included (mean age: 39.9 ± 4.6, BMI: 24.2 ± 3.9 kg/m2, endometrial thickness: 8.2 ± 1.4 mm). The percentage of endometria indicated as receptive by ERA® was 40.5%. When comparing receptive versus non-receptive groups, no differences were observed in baseline characteristics nor in steroid hormones levels in serum or endometrium. No association between serum P4 and endometrial steroid levels or ERA result was found (P < 0.05). When the population was stratified according to metabolite concentration levels, endometrial P4 and 17α-hydroxyprogesterone were significantly associated with endometrial receptivity (P < 0.05). A higher proportion of receptive endometria by ERA was observed when endometrial P4 levels were higher than 40.07 µg/ml (relative maximum) and a lower proportion of receptive endometria was associated with endometrial 17α-hydroxyprogesterone lower than 0.35 ng/ml (first quartile). A positive correlation R2 = 0.67, P < 0.001 was observed between endometrial P4 and 17α-hydroxyprogesterone levels.

LIMITATIONS, REASONS FOR CAUTION

This study did not analyse pregnancy outcomes. Further, the findings can only be extrapolated to HRT cycles with micronised vaginal progesterone for luteal phase support.

WIDER IMPLICATIONS OF THE FINDINGS

Our findings suggest that the combined benefits of different routes of progesterone administration for luteal phase support could be leveraged to ensure an adequate concentration of progesterone both in the uterus and in the bloodstream. Further studies will confirm whether this method can optimise both endometrial receptivity and live birth rate. Additionally, targeted treatment to increase P4 endometrial levels may normalise the timing of the window of implantation without needing to modify the progesterone administration day.

STUDY FUNDING/COMPETING INTEREST(S)

This research was supported by the IVI-RMA Valencia (1706-VLC-051-EL) and Consellería d'Educació, Investigació, Cultura, i esport Generalitat Valenciana (Valencian Government, Spain, GV/2018//151). Almudena Devesa-Peiro (FPU/15/01398) and Cristina Rodriguez-Varela (FPU18/01657) were supported by the FPU program fellowship from the Ministry of Science, Innovation and Universities (Spanish Government). P.D.-G. is co-inventor on the ERA patent, with non-economic benefits. The other authors have no competing interests.

TRIAL REGISTRATION NUMBER

NCT03456375.

Conformational control through co-operative nonconventional C-H...N hydrogen bonds

We report the design, synthesis, and crystal structure of a conjugated aryleneethynyl molecule, 2-(2-{4,5-dimethoxy-2-[2-(2,3,4-trifluorophenyl)ethynyl]phenyl}ethynyl)-6-[2-(pyridin-2-yl)ethynyl]pyridine, C₃₀H₁₇F₃N₂O₂, that adopts a planar rhombus conformation in the solid state. The molecule crystallizes in the space group P-1, with Z = 2, and features two intramolecular sp²-C-H...N hydrogen bonds that co-operatively hold the arylethynyl molecule in a rhombus conformation. The H atoms are activated towards hydrogen bonding since they are situated on a trifluorophenyl ring and the H...N distances are 2.470 (16) and 2.646 (16) Å, with C-H...N angles of 161.7 (2) and 164.7 (2)°, respectively. Molecular electrostatic potential calculations support the formation of C-H...N hydrogen bonds to the trifluorophenyl moiety. Hirshfeld surface analysis identifies a self-complementary C-H...O dimeric interaction between adjacent 1,2-dimethoxybenzene segments that is shown to be common in structures containing that moiety.

The WISHED Randomized Controlled Trial: Impact of an Interactive Health Communication Application on Home Dialysis Use in People With Chronic Kidney Disease

Background:

While home dialysis therapies are more cost effective and may offer improved health-related quality of life, uptake compared to in-center hemodialysis remains low.

Objective:

To test whether a web-based interactive health communication application (IHCA) compared to usual care would increase home dialysis use.

Design:

Randomized control trial

Setting:

Patients were recruited from 3 multidisciplinary kidney clinics across Ontario, Canada (Hamilton, Kingston, London).

Patients:

We included adults with advanced chronic kidney disease (CKD) followed in multidisciplinary kidney clinics. Patients who had not completed dialysis modality education, who did not have access to a home computer or the internet, who had significant hearing or vision impairment, who could not read/write/speak English, who had a medical contraindication for home dialysis, or who had selected conservative kidney care were excluded.

Measurements:

The primary outcome was any use of home dialysis (peritoneal dialysis or home hemodialysis) within 90 days of dialysis initiation. Secondary outcomes were social support, decision conflict and dialysis knowledge measured at baseline, 6 months and 1 year.

Methods:

Eligible patients were randomized to either usual care or the IHCA in addition to usual care in a 1:1 ratio. As part of usual care, all patients received education about dialysis modalities and kidney transplantation delivered by clinic nurses according to local practices. Randomization was performed using a computer-generated sequence in randomly permuted block sizes, stratified by site, and allocation occurred using sequentially numbered sealed, opaque envelopes. Participants, care providers, and outcome assessors were not blinded to the intervention. All analyses were performed blinded using an intention to treat approach. We estimated the effect of the ICHA on the odds of the primary outcome using unadjusted logistic regression models. Linear mixed models for repeated measures over time were used to analyze the impact of the IHCA on the secondary outcomes of interest.

Results:

We randomized 140 (usual care, n = 71; IHCA, n = 69) out of a planned 264 patients (mean [SD] age 61 [14.5] years, 65% men). Among patients randomized to the IHCA group that completed 6-month and 1-year follow-up visits, 56.8% and 71.4%, respectively, had not accessed the IHCA website within the past month. There were 23 (32.4%) and 26 (37.7%) patients in the usual care and IHCA groups who received a home dialysis therapy within 90 days of dialysis initiation (odds ratio, OR = 1.3, 95% CI = [0.6-2.5], P = .5). Among the 78 patients who initiated dialysis (n = 38 usual care, n = 40 IHCA), 60.5% and 65% in the usual care and IHCA groups received a home therapy within 90 days of dialysis initiation (OR = 1.2, 95% CI = [0.5-3.0], P = .7). Secondary outcomes did not differ by intervention group over time.

Limitations:

The trial was underpowered due to poor recruitment and use of the IHCA was low.

Conclusions:

We did not find evidence of a difference in home dialysis uptake with IHCA use, but our analyses were notably underpowered. The incorporation of greater patient engagement, qualitative research and design research, and pilot implementation may help future evaluations of strategies to improve home dialysis uptake.

Trial Registration:

ClinicalTrials.gov #NCT01403454, registration date: Jul 21, 2011

Reduced FSH and LH action: implications for medically assisted reproduction

Luteinizing hormone (LH) and follicle-stimulating hormone (FSH) play complementary roles in follicle development and ovulation via a complex interaction in the hypothalamus, anterior pituitary gland, reproductive organs, and oocytes. Impairment of the production or action of gonadotropins causes relative or absolute LH and FSH deficiency that compromises gametogenesis and gonadal steroid production, thereby reducing fertility. In women, LH and FSH deficiency is a spectrum of conditions with different functional or organic causes that are characterized by low or normal gonadotropin levels and low oestradiol levels. While the causes and effects of reduced LH and FSH production are very well known, the notion of reduced action has received less attention by researchers. Recent evidence shows that molecular characteristics, signalling as well as ageing, and some polymorphisms negatively affect gonadotropin action. These findings have important clinical implications, in particular for medically assisted reproduction in which diminished action determined by the afore-mentioned factors, combined with reduced endogenous gonadotropin production caused by GnRH analogue protocols, may lead to resistance to gonadotropins and, thus, to an unexpected hypo-response to ovarian stimulation. Indeed, the importance of LH and FSH action has been highlighted by the International Committee for Monitoring Assisted Reproduction Technologies (ICMART) in their definition of hypogonadotropic hypogonadism as gonadal failure associated with reduced gametogenesis and gonadal steroid production due to reduced gonadotropin production or action. The aim of this review is to provide an overview of determinants of reduced FSH and LH action that are associated with a reduced response to ovarian stimulation.

Controlling Topology within Halogen-Bonded Networks by Varying the Regiochemistry of the Cyclobutane-Based Nodes

The formation of a pair of extended networks sustained by halogen bonds based upon two regioisomers of a photoproduct, namely rctt-1,3-bis(4-pyridyl)-2,4-bis(phenyl)cyclobutane (ht-PP) and rctt-1,2-bis(4-pyridyl)-3,4-bis(phenyl)cyclobutane (hh-PP), that have varied topology is reported. These networks are held together via I⋯N halogen bonds between the photoproduct and the halogen-bond donor 1,4-diiodoperchlorobenzene (C₆I₂Cl₄). The observed topology in each solid is controlled by the regiochemical position of the halogen-bond accepting 4-pyridyl group. This paper demonstrates the ability to vary the topology of molecular networks by altering the position of the halogen bond acceptor within the cyclobutane-based node.

Arylethynyl Helices Supported by π-Stacking and Halogen Bonding

Co-crystallization of a pyridyl-containing arylethynyl (AE) moiety with 1,4-diiodotetrafluorobenzene leads to unique, figure-eight shaped helical motifs within the crystal lattice. A slight twist in the AE backbone allows each AE unit to simultaneously interact with haloarene units that are stacked on top of one another. Left-handed (M) and right-handed (P) helices are interspersed in a regular pattern throughout the crystal. The major driving forces for assembly are 1) halogen bonding between the pyridyl nitrogen atoms and the iodine substituents of the haloarene, with N⋅⋅⋅I distances between 2.81 and 2.84 Å, and 2) π-π stacking of the haloarenes, with distances of approximately 3.57 Å between centroids. Halogen bonding and π-π stacking not only work in concert, but also seem to mutually enhance one another. Calculations suggest that the presence of π-π stacking modestly intensifies the halogen bonding interaction by <0.2 kcal/mol; likewise, halogen bonding to the haloarene enhances the π-π stacking interaction by 0.59 kcal/mol.

Iodoperchlorobenzene acts as a dual halogen-bond donor to template a [2 + 2] cycloaddition reaction within an organic co-crystal

The formation of three isostructural co-crystals that utilize iodoperchlorobenzene as a dual halogen-bond donor is reported.

Correction to: EStradiol and PRogesterone in In vitro ferTilization (ESPRIT): a multicenter study evaluating third‑ versus second‑generation estradiol and progesterone immunoassays

The article "EStradiol and PRogesterone in In vitro ferTilization (ESPRIT): a multicenter study evaluating third‑ versus second‑generation estradiol and progesterone immunoassays.

EStradiol and PRogesterone in In vitro ferTilization (ESPRIT): a multicenter study evaluating third- versus second-generation estradiol and progesterone immunoassays

PURPOSE

To assess estradiol (E₂) and progesterone levels during ovarian stimulation determined by third-generation (Gen III) and second-generation (Gen II) Elecsys^® immunoassays.

METHODS

E₂ and progesterone concentrations were measured using Elecsys^® Gen III and Gen II immunoassays, and progesterone concentrations on the day of ovulation triggering were determined by LC-MS/MS. This was a retrospective, non-interventional study conducted at European tertiary referral infertility clinics in women aged 18-45 years, with a body mass index 18-35 kg/m², regular menses, and both ovaries.

RESULTS

Serum samples were obtained from 230 women classified by oocyte retrieval as poor (33.0%; 0-3 oocytes), normal (40.9%; 4-15 oocytes), or high (26.1%; > 15 oocytes) responders. E₂ and progesterone levels increased during ovarian stimulation, with greatest increases observed in high responders. Elecsys^® Gen III and Gen II assay results were highly correlated for E₂ (Pearson's r = 0.99) and progesterone (r = 0.89); Gen III results were lower than Gen II for both E₂ and progesterone. On the day of triggering, Gen III E₂ and progesterone levels showed a difference of - 15.0% and - 27.9%, respectively. Progesterone levels (on day of triggering) measured by LC-MS/MS correlated better with Gen III (0.98) than Gen II (0.90). Mean relative differences for Gen III and Gen II assays versus LC-MS/MS were 14.6% and 62.8%, respectively.

CONCLUSION

E₂ and progesterone levels determined with Elecsys^® Gen II and III assays were highly correlated; results were lower for Gen III versus Gen II. Differences observed for progesterone on the day of triggering may be clinically relevant.

ALWAYS ICSI? A SWOT analysis

PURPOSE

Intracytroplasmatic sperm injection (ICSI) is a common procedure used to improve reproductive results, even among couples without male factor infertility. However, the evidence available is still uncertain on the possible advantages and deficiencies that this procedure may have in patients with no formal indication for ICSI.

METHODS

A SWOT (strengths, weaknesses, opportunities, threats) analysis examines the possible advantages and deficiencies of performing ICSI in these patients with no formal indication.

RESULTS

The evidence suggests that ICSI is not justified for non-male factor infertile couples requiring in vitro conception. One of the major strengths associated to the procedure is the virtual elimination of cases further complicated by total fertilization failure and a combination between IVF and ICSI on sibling oocytes has been advised in the literature. Greater technical difficulties, higher costs and performing an unnecessary invasive technique in some cases represent some of the weaknesses of the procedure, and questions regarding safety issues should not be ruled out.

CONCLUSION

Despite the widespread use of ICSI in patients without a formal diagnosis of male factor infertility, evidence demonstrating its effectiveness in this population is still lacking. Additional large and well-designed randomized controlled trials are needed to clarify definitive indications for ICSI in non-male factor infertility.

Crystal structure and photoreactivity of a halogen-bonded cocrystal based upon 1,2-diiodoperchlorobenzene and 1,2-bis(pyridin-4-yl)ethylene

The formation of a photoreactive cocrystal based upon 1,2-diiodoperchlorobenzene (1,2-C₆I₂Cl₄) and trans-1,2-bis(pyridin-4-yl)ethylene (BPE) has been achieved. The resulting cocrystal, 2(1,2-C₆I₂Cl₄)·(BPE) or C₆Cl₄I₂·0.5C₁₂H₁₀N₂, comprises planar sheets of the components held together by the combination of I...N halogen bonds and halogen-halogen contacts. Notably, the 1,2-C₆I₂Cl₄ molecules π-stack in a homogeneous and face-to-face orientation that results in an infinite column of the halogen-bond donor. As a consequence of this stacking arrangement and I...N halogen bonds, molecules of BPE also stack in this type of pattern. In particular, neighbouring ethylene groups in BPE are found to be parallel and within the accepted distance for a photoreaction. Upon exposure to ultraviolet light, the cocrystal undergoes a solid-state [2 + 2] cycloaddition reaction that produces rctt-tetrakis(pyridin-4-yl)cyclobutane (TPCB) with an overall yield of 89%. A solvent-free approach utilizing dry vortex grinding of the components also resulted in a photoreactive material with a similar yield.

Ditopic halogen bonding with bipyrimidines and activated pyrimidines

The potential of pyrimidines to serve as ditopic halogen-bond acceptors is explored. The halogen-bonded cocrystals formed from solutions of either 5,5'-bipyrimidine (C₈H₆N₄) or 1,2-bis(pyrimidin-5-yl)ethyne (C₁₀H₆N₄) and 2 molar equivalents of 1,3-diiodotetrafluorobenzene (C₆F₄I₂) have a 1:1 composition. Each pyrimidine moiety acts as a single halogen-bond acceptor and the bipyrimidines act as ditopic halogen-bond acceptors. In contrast, the activated pyrimidines 2- and 5-{[4-(dimethylamino)phenyl]ethynyl}pyrimidine (C₁₄H₁₃N₃) are ditopic halogen-bond acceptors, and 1:1 halogen-bonded cocrystals are formed from 1:1 mixtures of each of the activated pyrimidines and either 1,2- or 1,3-diiodotetrafluorobenzene. A 1:1 cocrystal was also formed between 2-{[4-(dimethylamino)phenyl]ethynyl}pyrimidine and 1,4-diiodotetrafluorobenzene, while a 2:1 cocrystal was formed between 5-{[4-(dimethylamino)phenyl]ethynyl}pyrimidine and 1,4-diiodotetrafluorobenzene.

Application of a tetrapyrimidyl cyclobutane synthesized in the organic solid state: a halogen-bonded supramolecular ladder

A supramolecular ladder sustained by halogen bonds with rungs based upon a photoproduct, namely rctt-tetrakis(5′-pyrimidyl)cylcobutane, generated in the solid state is reported.

Triple-Pnictogen Bonding as a Tool for Supramolecular Assembly

Supramolecular assembly utilizing simultaneous formation of three pnictogen bonds around a single antimony vertex was explored via X-ray crystallography, solution NMR, and computational chemistry. An arylethynyl (AE) ligand was designed to complement the three electrophilic regions around the Sb compound. Though solution studies reveal large binding constants for individual pyridyl units with the Sb donor, the rigidity and prearrangement of the AE acceptor proved necessary to achieve simultaneous binding of three acceptors to the Sb-centered pnictogen-bond donor. Calculations and X-ray structures suggest that negative cooperativity upon sequential binding of three acceptors to a Sb center limits the utility of triple-pnictogen bonding pyridyl acceptors. These limitations can be negated, however, when positive cooperativity is designed into a complementary acceptor ligand.

1,2,4,5-Tetrachloro-3,6-diiodobenzene benzene monosolvate

The title compound, C6Cl4I2·C6H6, crystallizes from benzene solution as cube-shaped crystals in the triclinic space group P\overline{1} with Z = 1. The asymmetric unit of the crystal structure contains one half of each molecule. In the crystal, the benzene ring is almost orthogonal to the perhalobenzene ring and the molecules are linked by C—I...π interactions, with a close contact between the iodine atom and the benzene ring of 3.412 (1) Å.

Patterns of genetic structure and adaptive positive selection in the Lithuanian population from high-density SNP data

The analysis of geographically specific regions and the characterization of fine-scale patterns of genetic diversity may facilitate a much better understanding of the microevolutionary processes affecting local human populations. Here we generated genome-wide high-density SNP genotype data in 425 individuals from six geographical regions in Lithuania and combined our dataset with available ancient and modern data to explore genetic population structure, ancestry components and signatures of natural positive selection in the Lithuanian population. Our results show that Lithuanians are a homogenous population, genetically differentiated from neighbouring populations but within the general expected European context. Moreover, we not only confirm that Lithuanians preserve one of the highest proportions of western, Scandinavian and eastern hunter-gather ancestry components found in European populations but also that of an steppe Early to Middle Bronze Age pastoralists, which together configure the genetic distinctiveness of the Lithuanian population. Finally, among the top signatures of positive selection detected in Lithuanians, we identified several candidate genes related with diet (PNLIP, PPARD), pigmentation (SLC24A5, TYRP1 and PPARD) and the immune response (BRD2, HLA-DOA, IL26 and IL22).

Crystal structure of the co-crystal salt 2-amino-6-bromo-pyridinium 2,3,5,6-tetra-fluoro-benzoate

The title compound crystallized from an equimolar mixture of 2-amino-6-bromo­pyridine and 2,3,5,6-tetra­fluoro­benzoic acid in absolute ethanol.

The asymmetric unit of the co-crystal salt 2-amino-6-bromo­pyridinium 2,3,5,6-tetra­fluoro­benzoate, C₅H₆BrN₂⁺·C₇HF₄O₂⁻, contains one pyridinium cation and one benzoate anion. In the crystal, the amino­pyridinium cationic unit forms two hydrogen bonds to the benzoate oxygen atoms in an R₂²(8) motif. Two pyridinium benzoate units are hydrogen bonded through self-complementary hydrogen bonds between the second amine hydrogen and a carboxyl­ate O with a second R₂²(8) motif to form a discrete hydrogen-bonded complex containing two 2-amino-6-bromo­pyridinium moieties and two 2,3,5,6-tetra­fluoro­benzoate moieties. The 2-amino-6-bromo­pyridinium moieties π-stack in a head-to-tail mode with a centroid–centroid separation of 3.7227 (12) Å and adjacent tetra­fluoro­benzoates also π-stack in a head-to-tail mode with a centroid–centroid separation of 3.6537 (13) Å.

Effects of dynamic pedal motion and static disorder on thermal expansion within halogen-bonded co-crystals

Thermal expansion is investigated for halogen-bonded co-crystals containing molecules that exhibit dynamic motion, lack motion ability, or experience static disorder.

Regioselective [2 + 2] cycloaddition reaction within a pair of polymorphic co-crystals based upon halogen bonding interactions

A pair of photoreactive polymorphic co-crystals that undergo a regioselective solid-state [2 + 2] cycloaddition reaction that yields exclusively the head-to-tail photoproduct is reported.

Infinite and discrete halogen bonded assemblies based upon 1,2-bis(iodoethynyl)benzene

Infinite and discrete co-crystals based upon 1,2-bis(iodoethynyl)benzene as a halogen bond donor to either a symmetrical bipyridine or an unsymmetrical monopyridine-based acceptor is reported.

1-(2-Amino-4,5-dimethylphenyl)ethanone

The molecule of the title compound, C10H13NO, also referred to as 2-amino-4,5-dimethylacetophenone, lies on a crystallographic mirror plane with four molecules in the orthorhombic unit cell and features an intramolecular N—H...O hydrogen bond. In the crystal, the molecules are linked by N—H...O hydrogen bonds, forming ribbons along theaaxis that pack to form sheets lying in the (010) plane.