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1.
J Am Chem Soc ; 2024 Jun 06.
Artículo en Inglés | MEDLINE | ID: mdl-38843775

RESUMEN

The quest for planar hypercoordinate atoms (phA) beyond six has predominantly focused on transition metals, with dodecacoordination being the highest reported thus far. Extending this bonding scenario to main-group elements, which typically lack d orbitals despite their larger atomic radius, has posed significant challenges. Intrigued by the potentiality of covalent bonding formation using the d orbitals of the heavier alkaline-earth metals (Ae = Ca, Sr, Ba), the so-called "honorary transition metals", we aim to push the boundaries of planar hypercoordination. By including rings formed by 12-15 atoms of boron-carbon and Ae centers, we propose a design scheme of 180 candidates with a phA. Further systematic screening, structural examination, and stability assessments identified 10 potential clusters with a planar hypercoordinate alkaline-earth metal (phAe) as the lowest-energy form. These unconventional structures embody planar dodeca-, trideca-, tetradeca-, and pentadecacoordinate atoms. Chemical bonding analyses reveal the important role of Ae d orbitals in facilitating covalent interactions between the central Ae atom and the surrounding boron-carbon rings, thereby establishing a new record for coordination numbers in the two-dimensional realm.

2.
Chemistry ; 30(1): e202302415, 2024 Jan 02.
Artículo en Inglés | MEDLINE | ID: mdl-37955853

RESUMEN

Nowadays, an active research topic is the connection between Clar's rule, aromaticity, and magnetic properties of polycyclic benzenoid hydrocarbons. In the present work, we employ a meticulous magnetically induced current density analysis to define the net current flowing through any cyclic circuit, connecting it to aromaticity based on the ring current concept. Our investigation reveals that the analyzed polycyclic systems display a prominent global ring current, contrasting with subdued semi-local and local ring currents. These patterns align with Clar's aromatic π-sextets only in cases where migrating π-sextet structures are invoked. The results of this study will enrich our comprehension of aromaticity and magnetic behavior in such systems, offering significant insights into coexisting ring current circuits in these systems.

3.
Chemphyschem ; 25(12): e202400271, 2024 Jun 17.
Artículo en Inglés | MEDLINE | ID: mdl-38530286

RESUMEN

This study comprehensively analyzes the magnetically induced current density of polycyclic compounds labeled as "aromatic chameleons" since they can arrange their π-electrons to exhibit aromaticity in both the ground and the lowest triplet state. These compounds comprise benzenoid moieties fused to a central skeleton with 4n π-electrons and traditional magnetic descriptors are biased due to the superposition of local magnetic responses. In the S0 state, our analysis reveals that the molecular constituent fragments preserve their (anti)aromatic features in agreement with two types of resonant structures: one associated with aromatic benzenoids and the other with a central antiaromatic ring. Regarding the T1 state, a global and diatropic ring current is revealed. Our aromaticity study is complemented with advanced electronic and geometric descriptors to consider different aspects of aromaticity, particularly important in the evaluation of excited state aromaticity. Remarkably, these descriptors consistently align with the general features on the main delocalization pathways in polycyclic hydrocarbons consisting of fused 4n π-electron rings. Moreover, our study demonstrates an inverse correlation between the singlet-triplet energy difference and the antiaromatic character of the central ring in S0.

4.
J Phys Chem A ; 128(24): 4806-4813, 2024 Jun 20.
Artículo en Inglés | MEDLINE | ID: mdl-38839423

RESUMEN

Recently, Guha and co-workers (Sarmah, K.; Kalita, A.; Purkayastha, S.; Guha, A. K. Pushing The Extreme of Multicentre Bonding: Planar Pentacoordinate Hydride. Angew. Chem. Int. Ed. 2024, e202318741) reported a highly intriguing bonding motif: planar pentacoordinate hydrogen (ppH) in Li5H6-, featuring C2v symmetry in the singlet state with two distinct H-Li (center-ring) bond distances. We herein revisited the potential energy surface of Li5H6- by using a target-oriented genetic algorithm. Our investigation revealed that the lowest-energy structure of Li5H6- exhibits a ppH configuration with very high D5h symmetry and a 1A1' electronic state. We did not find any electronic effect like Jahn-Teller distortion that could be responsible for lowering its symmetry. Moreover, our calculations demonstrated significant differences in the relative energies of other low-lying isomers. An energetically very competitive planar tetracoordinate hydrogen (ptH) isomer is also located, but it corresponds to a very shallow minimum on the potential energy surface depending on the used level of theory. Chemical bonding analyses, including AdNDP and EDA-NOCV, uncover that the optimal Lewis structure for Li5H6- involves H- ions stabilized by the Li5H5 crown. Surprisingly, despite the dominance of electrostatic interactions, the contribution from covalent bonding is also significant between ppH and the Li5H5 moiety, derived from H-(1s) → Li5H5 σ donation. Magnetically induced current density analysis revealed that due to minimal orbital overlap and the highly polar nature of the H-Li covalent interaction, the ppH exhibits local diatropic ring currents around the H centers, which fails to result in a global aromatic ring current. The coordination of Li5H6- with Lewis acids, BH3 and BMe3, instantly converts the ppH configuration to (quasi) ptH. These Lewis acid-bound ptH complexes show high electronic stability and high thermochemical stability against dissociation and, therefore, will be ideal candidates for the experimental realization.

5.
Am J Drug Alcohol Abuse ; 50(4): 481-491, 2024 Jul 03.
Artículo en Inglés | MEDLINE | ID: mdl-39158536

RESUMEN

Background: Many national studies fail to account for discordance between sexual orientation dimensions (e.g. a mismatch between sexual identity and sexual attraction) or sexual identity fluidity (e.g. changes in sexual identity over time).Objective: To examine the longitudinal relationships among sexual identity fluidity/stability, sexual orientation discordance/concordance, and alcohol and other drug use disorder symptoms.Methods: The study used nationally representative longitudinal data from Waves 1-5 (2013-2019) of the Population Assessment of Tobacco and Health (PATH) study of US adolescents and adults (N = 24,591).Results: Substance use disorder symptoms were most prevalent (45.8%) among bisexual-stable females relative to all other sexual identity subgroups. The adjusted odds ratios (AORs) of substance use disorder symptoms were significantly higher among bisexual-stable females vs. heterosexual-stable females in all models (AOR range: 1.94-2.32), while no such associations were found for males. Sexual identity-attraction discordant females had significantly greater AORs (17/20 instances) of substance use disorder symptoms compared to concordant females; this finding was not as consistent for males (6/20 instances).Conclusion: Sexual orientation discordance was significantly associated with substance use disorder symptoms, especially among females discordant in their sexual identity and attraction. Bisexual-stable and discordant females are at highest risk of developing symptomatic substance use; it is vital that they receive screening, no matter where they are in their coming out process. This study highlights pitfalls of relying solely on cross-sectional data using a single sexual orientation dimension to understand the relationship between sexual orientation and substance use disorder.


Asunto(s)
Conducta Sexual , Trastornos Relacionados con Sustancias , Humanos , Femenino , Estudios Longitudinales , Masculino , Trastornos Relacionados con Sustancias/epidemiología , Adulto , Adolescente , Adulto Joven , Estados Unidos/epidemiología , Minorías Sexuales y de Género/estadística & datos numéricos , Persona de Mediana Edad , Bisexualidad/estadística & datos numéricos , Prevalencia
6.
Angew Chem Int Ed Engl ; 63(5): e202317848, 2024 Jan 25.
Artículo en Inglés | MEDLINE | ID: mdl-38087836

RESUMEN

When (4n +2) π-electrons are located in single planar ring, it conventionally qualifies as aromatic. According Hückel's rule, systems possessing ten π-electrons should be aromatic. Herein we report a series of D5h  Li6 E5 Li6 sandwich structures, representing the first global minima featuring ten π-electrons E5 10- ring (E=Si-Pb). However, these π-electrons localize as five π-lone-pairs rather than delocalized orbitals. The high symmetry structure achieved is a direct consequence of σ-aromaticity, particularly favored in elements from Si to Pb, resulting in a pronounced diatropic ring current flow that contributes to the enhanced stability of these systems.

7.
Phys Chem Chem Phys ; 25(30): 20235-20240, 2023 Aug 02.
Artículo en Inglés | MEDLINE | ID: mdl-37477548

RESUMEN

Using various exploration strategies, in this study, we investigated the potential energy surfaces (PES) of CBe5H5+ and CnBe3n+2H2n+22+ (n = 2-4) clusters. Previous studies proposed that the planar pentacoordinate carbons (ppCs) were the global minima of these clusters. However, our study identified new putative global minima and competitive isomers, refuting some previous assignments. We employed several methods, including evolutive-inspired stochastic approaches guided by "chemical criteria", and ab initio molecular dynamics simulations at elevated temperatures. Our results showed that the size of the scanned population significantly affected the evolutive method and that constrained or guided procedures showed an advantage in identifying better minima for larger systems. This study demonstrated that using multiple complementary strategies can result in a wider variety of minima in a given energy range. Our findings provide valuable insights into exploring the potential energy surfaces of clusters, mainly medium-sized clusters, which could be the connections between small clusters and nanomaterials.

8.
Can J Psychiatry ; 68(6): 461-469, 2023 06.
Artículo en Inglés | MEDLINE | ID: mdl-36632009

RESUMEN

OBJECTIVES: To examine whether sexual and gender minority (SGM) emerging adults perceived their SGM status was linked to suicidal ideation, and to explore if their responses fell within tenets of the minority stress framework. METHOD: Open text (survey) responses of Dutch and Flemish SGM emerging adults (n = 187) were thematically analysed using the constant comparative comparison method for qualitative analysis. RESULTS: We identified 8 themes in our qualitative analysis. Two themes fell within the scope of the minority stress framework that has received little attention: (1) concerns about relationships and family planning and (2) feeling different (internal stressor). Two additional themes emerged largely beyond the scope of existing minority stress framework studies on suicidality: (3) SGM-related questioning; (4) negativity in LGBT communities. Four established minority stress framework themes emerged: (5) gender identity stress; (6) victimization; (7) coming-out stress; (8) psychological difficulties linked to SGM status. CONCLUSION: Suicide prevention needs to focus on supporting SGM emerging adults who worry about feeling "different", or who have concerns over their romantic and family life, on reducing gender minority stress, as well as on caring for those who are victimized due to their sexual or gender identity.


Asunto(s)
Identidad de Género , Minorías Sexuales y de Género , Humanos , Femenino , Adulto , Masculino , Ideación Suicida , Conducta Sexual/psicología , Emociones
9.
Behav Med ; 49(1): 62-71, 2023.
Artículo en Inglés | MEDLINE | ID: mdl-34749595

RESUMEN

Household job loss during COVID-19 constitutes a public health crisis. Research suggests associations between household job loss, harsher parenting practices, and mental health challenges in the general population. Sexual minority adolescents (SMA) face high rates of family stress and rejection, but evidence linking household job loss to SMA mental health is lacking. This study evaluated associations between household job loss, family rejection, and mental health with a national sample of SMA who were sheltering in place with families during the pandemic. SMA from an ongoing prospective study completed an online questionnaire between May 13-31, 2020. It was hypothesized that household job loss during the pandemic would be associated with elevated depressive and anxiety symptoms through family rejection. Household job loss during the pandemic was indirectly associated with SMA mental health through family rejection. These findings highlight how socioeconomic change and policy carry implications for SMA health.


Asunto(s)
COVID-19 , Minorías Sexuales y de Género , Humanos , Adolescente , Estados Unidos/epidemiología , Salud Mental , Estudios Prospectivos , Ansiedad/epidemiología
10.
J Clin Psychol ; 79(4): 1130-1155, 2023 04.
Artículo en Inglés | MEDLINE | ID: mdl-36459589

RESUMEN

BACKGROUND: Research has shown that sexual minority people of color experience pervasive and sometimes severe life stressors that increase their risk of experiencing mental health problems, and that can contribute to lifelong health disparities. However, no studies in this population have investigated stressor exposure occurring over the entire lifespan. Moreover, it remains unknown whether these stressor-health effects differ based on the timing or types of stressors experienced. PURPOSE: The purpose of this study is to examine how cumulative lifetime stressor exposure is associated with mental health among Black, Latinx, and biracial Black-Latinx sexual minority persons. METHOD: Participants were 285 ethnic/racial minority young adults (Mage = 25.18 years old, SD = 1.94, age range = 19-29 years), who completed the Stress and Adversity Inventory for Adults to assess for retrospective reports of lifetime stressor count and severity. The Brief Symptom Inventory was used to assess participants' symptoms of anxiety, depression, and somatization, which were the main outcomes. Most participants identified as cisgender male (94.7%) and gay (74.2%), with the remaining participants identifying as transgender or genderqueer/nonbinary for gender and bisexual/pansexual, queer, or another sexual orientation. RESULTS: Multiple regression analyses indicated that experiencing more-and more severe-stressors across the lifespan was related to greater anxiety, depressive, and somatization symptoms. These effects were robust while controlling for race/ethnicity, sexual orientation, education, and employment status, and they differed based on stressor exposure timing, type, primary life domain, and core social-psychological characteristic. CONCLUSION: Greater cumulative lifetime stressor exposure is related to poorer mental health among sexual minority people of color. Screening for lifetime stressors may thus help identify at-risk persons and provide an opportunity to intervene to help mitigate or prevent mental health disparities in multiply stigmatized adults.


Asunto(s)
Salud Mental , Minorías Sexuales y de Género , Adulto Joven , Humanos , Masculino , Femenino , Adulto , Estudios Retrospectivos , Pigmentación de la Piel , Estrés Psicológico/psicología , Conducta Sexual/psicología
11.
Angew Chem Int Ed Engl ; 62(31): e202304997, 2023 Aug 01.
Artículo en Inglés | MEDLINE | ID: mdl-37268596

RESUMEN

Planar boron clusters have often been regarded as "π-analogous" to aromatic arenes because of their similar delocalized π-bonding. However, unlike arenes such as C5 H5 - and C6 H6 , boron clusters have not previously shown the ability to form sandwich complexes. In this study, we present the first sandwich complex involving beryllium and boron, B7 Be6 B7 . The global minimum of this combination adopts a unique architecture having a D6h geometry, featuring an unprecedented monocyclic Be6 ring sandwiched between two quasi-planar B7 motifs. The thermochemical and kinetic stability of B7 Be6 B7 can be attributed to strong electrostatic and covalent interactions between the fragments. Chemical bonding analysis shows that B7 Be6 B7 can be considered as a [B7 ]3- [Be6 ]6+ [B7 ]3- complex. Moreover, there is a significant electron delocalization within this cluster, supported by the local diatropic contributions of the B7 and Be6 fragments.

12.
Chemphyschem ; 23(19): e202200366, 2022 10 06.
Artículo en Inglés | MEDLINE | ID: mdl-35785508

RESUMEN

A low-lying structure is revealed for the CuB12 - cluster, which is bowl-shaped. It consists of a triangular CuB2 base and a B10 rim. Molecular dynamics simulations indicates its structural robustness; at an elevated temperature (600 K), the base rotates reversibly within the B10 perimeter. Chemical bonding analysis detects 2σ- and 3π-delocalized bonds, suggesting double aromaticity. This is also confirmed by two diatropic and concentric ring currents under an external magnetic field.

13.
Prev Sci ; 23(1): 142-153, 2022 01.
Artículo en Inglés | MEDLINE | ID: mdl-34482516

RESUMEN

Little research has examined subtle, intersectional, and everyday minority stress, such as microaggressions specific to being a queer person of color, and its associations with depressive symptoms among sexual and gender minority adolescents (SGMA) of color. Moreover, research is needed to identify mechanisms that might explain the associations between minority stress and depression. This study examined the associations between subtle and intersectional minority stress (i.e., SGMA of color-specific microaggressions) and depressive symptoms among SGMA of color and tested self-concept factors (i.e., self-esteem and sense of mastery) as mediators of these associations. A large national US sample of SGMA of color (N = 3398; 31.8% transgender; 55.7% plurisexual) ages 13 to 17 years (M = 15.56, SD = 1.27) were recruited online. Participants' race/ethnicity were Asian/Pacific Islander (12.2%), Black/African American (13.2%), Hispanic/Latina(o)/x (30%), Native American/Alaska Native (1.2%), Middle Eastern (1.9%), Biracial or Multiracial (40%), and other racial/ethnic minority groups (1.7%). Over and above the effects of racism and SGM-based victimization, subtle intersectional minority stressors were associated with greater depressive symptoms and lower self-esteem and sense of mastery. Mediation analyses indicated that subtle intersectional minority stressors had indirect effects on depressive symptoms through lower self-esteem and sense of mastery for the aggregate sample of SGMA of color and most racial/ethnic groups in the sample. The results demonstrate that subtle and intersectional minority stress is a unique and significant form of minority stress that is a risk factor for depressive symptoms for SGMA of color. Moreover, our findings underscore self-concept mechanisms as targets for prevention and intervention.


Asunto(s)
Racismo , Minorías Sexuales y de Género , Adolescente , Depresión , Etnicidad , Humanos , Grupos Minoritarios
14.
Molecules ; 28(1)2022 Dec 28.
Artículo en Inglés | MEDLINE | ID: mdl-36615438

RESUMEN

Here, it is shown that the M3B12 (M = Cu-Au) clusters' global minima consist of an elongated planar B12 fragment connected by an in-plane linear M3 fragment. This result is striking since this B12 planar structure is not favored in the bare cluster, nor when one or two metals are added. The minimum energy structures were revealed by screening the potential energy surface using genetic algorithms and density functional theory calculations. Chemical bonding analysis shows that the strong electrostatic interactions with the metal compensate for the high energy spent in the M3 and B12 fragment distortion. Furthermore, metals participate in the delocalized π-bonds, which infers an aromatic character to these species.


Asunto(s)
Cromatografía de Gases , Electricidad Estática
15.
Chemistry ; 27(67): 16701-16706, 2021 Dec 01.
Artículo en Inglés | MEDLINE | ID: mdl-34617347

RESUMEN

After exploring the potential energy surfaces of Mm CE2 p (E=S-Te, M=Li-Cs, m=2, 3 and p=m-2) and Mn CE3 q (E=S-Te, M=Li-Cs, n=1, 2, q=n-2) combinations, we introduce 38 new global minima containing a planar hypercoordinate carbon atom (24 with a planar tetracoordinate carbon and 14 with a planar pentacoordinate carbon). These exotic clusters result from the decoration of V-shaped CE2 2- and Y-shaped CE3 2- dianions, respectively, with alkali counterions. All these 38 systems fulfill the geometrical and electronic criteria to be considered as true planar hypercoordinate carbon systems. Chemical bonding analyses indicate that carbon is covalently bonded to chalcogens and ionically connected to alkali metals.

16.
Chemphyschem ; 22(10): 906-910, 2021 05 17.
Artículo en Inglés | MEDLINE | ID: mdl-33779015

RESUMEN

We report the global minima structures of Li8 Si8 , Li10 Si9 , and Li12 Si10 systems, in which silicon moieties maintain structural and chemical bonding characteristics similar to those of their building blocks: the aromatic clusters Td -Li4 Si4 and C2v -Li6 Si5 . Electron counting rules, chemical bonding analysis, and magnetic response properties verify the silicon unit's aromaticity persistence. This study demonstrates the feasibility of assembling silicon-based nanostructures from aromatics clusters as building blocks.

17.
J Phys Chem A ; 125(14): 3009-3014, 2021 Apr 15.
Artículo en Inglés | MEDLINE | ID: mdl-33797250

RESUMEN

The exhaustive exploration of the potential energy surfaces of CE2M2 (E = Si-Pb; M = Li and Na) revealed seven global minima containing a planar tetracoordinate carbon (ptC). The design, based on a π-localization strategy, resulted in a ptC with two double bonds forming a linear or a bent allene-type E═C═E motif. The magnetic response of the bent E═C═E fragments support a σ-aromaticity. The bonding analysis indicated that the ptCs form C-E covalent bonds and C-M electrostatic interactions.

18.
Arch Sex Behav ; 50(3): 983-1001, 2021 04.
Artículo en Inglés | MEDLINE | ID: mdl-33398694

RESUMEN

Sexual minority emerging adults are more likely to engage in suicidal ideation than their heterosexual counterparts. Experiences of homophobic violence are associated with suicidal ideation. Yet, the specific mechanisms linking homophobic violence to suicidal ideation remain unclear. Entrapment and social belongingness were tested to determine their relevance for understanding the link between homophobic violence and suicidal ideation. A sample of sexual minority Dutch emerging adults (N = 675; ages 18-29, M = 21.93 years, SD = 3.20) were recruited through online platforms and flyers. Homophobic violence was expected to be positively associated with suicidal ideation and entrapment. The association between homophobic violence and suicidal ideation was expected to be indirectly linked through entrapment. We explored whether various sources of social belongingness moderated the path between entrapment and suicidal ideation and whether those sources of social belongingness moderated the indirect effect of homophobic violence on suicidal ideation through entrapment. Results showed that homophobic violence and entrapment were positively associated with suicidal ideation and that family belongingness was negatively associated with suicidal ideation. Homophobic violence and suicidal ideation were not indirectly linked through entrapment. The interaction effect between entrapment and family belongingness was significant, suggesting that, on average, the effect of entrapment on suicidal ideation decreased when family belongingness was high. These results suggest that family belongingness may reduce the association between entrapment and suicidal ideation while adjusting for homophonic violence. Reducing entrapment and improving family belongingness may be useful targets for programs aimed at preventing suicidal ideation among sexual minority emerging adults.


Asunto(s)
Relaciones Familiares/psicología , Minorías Sexuales y de Género/psicología , Ideación Suicida , Adolescente , Adulto , Humanos , Masculino , Países Bajos , Factores de Riesgo , Adulto Joven
19.
Angew Chem Int Ed Engl ; 60(16): 8700-8704, 2021 Apr 12.
Artículo en Inglés | MEDLINE | ID: mdl-33527696

RESUMEN

Herein, the first global minima containing a planar hexacoordinate carbon (phC) atom are reported. The fifteen structures belong to the CE3 M3 + (E=S-Te and M=Li-Cs) series and satisfy both geometric and electronic criteria to be considered as a true phC. The design strategy consisted of replacing oxygen in the D3h  CO3 Li3 + structure with heavy and less electronegative chalcogens, inducing a negative charge on the C atom and an attractive electrostatic interaction between C and the alkali-metal cations. The chemical bonding analyses indicate that carbon is covalently bonded to three chalcogens and ionically connected to the three alkali metals.

20.
J Res Adolesc ; 29(3): 724-735, 2019 09.
Artículo en Inglés | MEDLINE | ID: mdl-29791037

RESUMEN

Retrospective peer victimization reports may be inaccurate. With an ethnically and sexually diverse sample, this study compared adolescents' self-reported peer victimization in 6th grade to their own retrospective reports of 6th-grade victimization when they were in the 12th grade, controlling for past and current adjustment. Overall, 12th graders' retrospective victimization reports correlated with their own earlier 6th-grade self-reports and there was a general tendency to underreport retrospectively. Underreporters were distinguished by worse past 6th-grade adjustment, whereas overreporters were distinguished by worse current (12th-grade) adjustment. Higher current depressive symptoms and social anxiety, and lower current self-worth may be important control variables when collecting retrospective reports of victimization because current adjustment may augment participants' recollection of past experiences.


Asunto(s)
Acoso Escolar/psicología , Víctimas de Crimen/psicología , Etnicidad/psicología , Minorías Sexuales y de Género/psicología , Estudiantes/psicología , Adolescente , Acoso Escolar/estadística & datos numéricos , Niño , Víctimas de Crimen/estadística & datos numéricos , Depresión/epidemiología , Depresión/psicología , Etnicidad/estadística & datos numéricos , Femenino , Humanos , Masculino , Grupo Paritario , Estudios Retrospectivos , Instituciones Académicas/estadística & datos numéricos , Autoimagen , Autoinforme/estadística & datos numéricos , Minorías Sexuales y de Género/estadística & datos numéricos , Ajuste Social , Adulto Joven
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