Penerapan Model Pembelajaran Atraktif Berbasis Multiple Intelligences Tentang Pemantulan Cahaya pada Cermin

Penelitian ini bertujuan untuk mengetahui efektivitas penerapan model pembelajaran atraktif berbasis multiple intelligences dalam meremediasi miskonsepsi siswa tentang pemantulan cahaya pada cermin. Pada penelitian ini digunakan bentuk pre-eksperimental design dengan rancangan one group pretest-post test design. Alat pengumpulan data berupa tes pilihan ganda dengan reasoning. Hasil validitas sebesar 4,08 dan reliabilitas 0,537. Siswa dibagi menjadi lima kelompok kecerdasan, yaitu kelompok linguistic intelligence, mathematical-logical intelligence, visual-spatial intelligence, bodily-khinestetic intelligence, dan musical intelligence. Siswa membahas konsep fisika sesuai kelompok kecerdasannya dalam bentuk pembuatan pantun-puisi, teka-teki silang, menggambar kreatif, drama, dan mengarang lirik lagu. Efektivitas penerapan model pembelajaran multiple intelligences menggunakan persamaan effect size. Ditemukan bahwa skor effect size masing-masing kelompok berkategori tinggi sebesar 5,76; 3,76; 4,60; 1,70; dan 1,34. Penerapan model pembelajaran atraktif berbasis multiple intelligences efektif dalam meremediasi miskonsepsi siswa. Penelitian ini diharapkan dapat digunakan pada materi fisika dan sekolah lainnya

Aluminum–Ligand Cooperative N–H Bond Activation and an Example of Dehydrogenative Coupling

Activation of N–H bonds by a molecular aluminum complex via metal–ligand cooperation is described. (^PhI₂P^2–)­AlH (<b>1b</b>), in which ^PhI₂P^2– is a tridentate bis­(imino)­pyridine ligand, reacts with anilines to give the N–H-activated products (^PhHI₂P^–)­AlH­(NHAr) (<b>2</b>). When heated, <b>2</b> releases H₂ and affords (^PhI₂P^–)­Al­(NHAr) (<b>3</b>). Complex <b>1b</b> catalyzes the dehydrogenative coupling of benzylamine to afford H₂, NH₃, and <i>N</i>-(phenylmethylene)­benzenemethanamine

Directing the Reactivity of [HFe₄N(CO)₁₂]⁻ toward H⁺ or CO₂ Reduction by Understanding the Electrocatalytic Mechanism

Selective reactivity of an electrocatalytically generated catalyst–hydride intermediate toward the hydrogen evolution reaction (HER) or reduction of CO₂ is key for a CO₂ reduction electrocatalyst. Under appropriate conditions, Et₄N[Fe₄N(CO)₁₂] (Et₄N-<b>1</b>) is a catalyst for the HER or for CO₂ conversion at −1.25 V vs SCE using a glassy carbon electrode

Directing the Reactivity of [HFe₄N(CO)₁₂]⁻ toward H⁺ or CO₂ Reduction by Understanding the Electrocatalytic Mechanism

Selective reactivity of an electrocatalytically generated catalyst–hydride intermediate toward the hydrogen evolution reaction (HER) or reduction of CO₂ is key for a CO₂ reduction electrocatalyst. Under appropriate conditions, Et₄N[Fe₄N(CO)₁₂] (Et₄N-<b>1</b>) is a catalyst for the HER or for CO₂ conversion at −1.25 V vs SCE using a glassy carbon electrode

Aluminum–Amido-Mediated Heterolytic Addition of Water Affords an Alumoxane

Addition of the O–H bonds in water across the aluminum–nitrogen bond of a molecular aluminum–amido complex affords an alumoxane. The reaction of (^PhI₂P^2–)­AlH (<b>1</b>) with water forms dimeric [(^PhHI₂P^–)­AlH]­(μ-O) (<b>2</b>) under mild conditions. Upon reaction of <b>2</b> with excess water [(^PhHI₂P^–)­Al­(OH)]­(μ-O) (<b>3</b>) is formed with liberation of H₂

Aluminum–Ligand Cooperative N–H Bond Activation and an Example of Dehydrogenative Coupling

Activation of N–H bonds by a molecular aluminum complex via metal–ligand cooperation is described. (^PhI₂P^2–)­AlH (<b>1b</b>), in which ^PhI₂P^2– is a tridentate bis­(imino)­pyridine ligand, reacts with anilines to give the N–H-activated products (^PhHI₂P^–)­AlH­(NHAr) (<b>2</b>). When heated, <b>2</b> releases H₂ and affords (^PhI₂P^–)­Al­(NHAr) (<b>3</b>). Complex <b>1b</b> catalyzes the dehydrogenative coupling of benzylamine to afford H₂, NH₃, and <i>N</i>-(phenylmethylene)­benzenemethanamine

A Sterically Demanding Iminopyridine Ligand Affords Redox-Active Complexes of Aluminum(III) and Gallium(III)

The combination of an electrophilic metal center with a redox active ligand set has the potential to provide reactivity unique from transition metal redox chemistry. In this report, substituted iminopyridine complexes containing monoanionic and dianionic ^MeIP_Mes ligands have been characterized structurally and electronically. Green (^MeIP_Mes^–)­AlCl₂ (<b>1</b>), (^MeIP_Mes^–)­AlMe₂ (<b>2</b>), and (^MeIP_Mes^–)­GaCl₂ (<b>5</b>) have a doublet spin state which results from the anion radical form of ^MeIP_Mes. Purple (^MeIP_Mes^2–)­AlCl­(OEt₂) (<b>3</b>), (^MeIP_Mes^2–)­AlMe­(OEt₂) (<b>4</b>), and (^MeIP_Mes^2–)­GaCl­(OEt₂) (<b>6</b>) are each diamagnetic. We have also investigated the solvent dependence of the decomposition of the ^MeIP_Mes anion radical. Complexes <b>1</b> and <b>2</b> can be obtained from benzene and hexanes whereas the use of ether solvents results in the formation of undesirable (^CH2IP_Mes^–)­AlCl₂ (<b>1a</b>) and (^CH2IP_Mes^–)­AlCl₂ (<b>2a</b>) formed by loss of a hydrogen atom from the ^MeIP_Mes^– ligand. Electrochemical measurements indicate that <b>1</b>, <b>2</b>, and <b>5</b> are redox active

Electrochemical Methods for Assessing Kinetic Factors in the Reduction of CO₂ to Formate: Implications for Improving Electrocatalyst Design

Thermochemical insights are often employed in the rationalization of reactivity and in the design of electrocatalysts for CO₂ reduction reactions targeting C–H bond-containing products. This work identifies experimental methods for assessing kinetic aspects of reactivity. These methods are illustrated using [Fe₄N­(CO)₁₂]⁻, which produces formate from CO₂ at −1.2 V versus SCE in either a MeCN/H₂O solvent (95:5) or pH 6.5 buffered water. Elementary rates for each reaction step are identified along with the rate-determining step (RDS) as C–H bond formation. Transition state kinetics were determined from an Eyring analysis for the rate-determining C–H bond formation step using temperature-dependent electrochemical measurements. A lower measured Δ<i>G</i>^⧧ (298 K, 12.3 ± 0.1 kcal mol^–1) in a pH 6.5 aqueous solution, compared with a Δ<i>G</i>^⧧(298 K) of 15.0 ± 0.1 kcal mol^–1 in a MeCN/H₂O solvent (95:5), correlates with faster observed reaction rates and provides a kinetic rationalization for the solvent-dependent chemistry. Taken together, the experimentally determined kinetic insights highlight that enhancement of the local concentration of CO₂ at catalyst–hydride sites should be a primary focus of ongoing catalyst design. This will both enhance reaction rates and increase selectivity for C–H bond formation over competing H–H bond formation, because that step is fast in H₂ evolution reactions

Mild Reduction Route to a Redox-Active Silicon Complex: Structure and Properties of (IP^2–)₂Si and (IP^–)₂Mg(THF) (IP = α-Iminopyridine)

Use of SiCl₄ as an organometallic reagent can be complicated by access to Si³⁺, Si²⁺, and unwanted sigmatropic rearrangements. Herein we report a mild reduction route, using (IP^–)₂Mg­(THF) (<b>1</b>) and Mg metal, to cleanly access (IP^2–)₂Si (<b>2</b>). Electrochemical measurements show that IP^2– is stabilized by Si⁴⁺ > Al³⁺ > Mg²⁺

(IP)₂Ga^III Complexes Facilitate Net Two-Electron Redox Transformations (IP = α‑Iminopyridine)

Reaction of M⁺[(IP^2‑)₂Ga]⁻ (IP = iminopyridine, M = Bu₄N, <b>1a</b>; (DME)₃Na, <b>1b</b>) with pyridine <i>N</i>-oxide affords two-electron-oxidized (IP^–)₂Ga­(OH) (<b>2</b>) in reactions where the product outcome is independent of the cation identity, M⁺. In a second example of <i>net</i> two-electron chemistry, outer sphere oxidation of M⁺[(IP^2‑)₂Ga]⁻ using either 1 or 2 equiv of the one-electron oxidant ferrocenium afforded [(IP^–)₂Ga]⁺ (<b>3</b>) in either 44 or 87% yield, respectively. Reaction with 1 equiv of TEMPO, a one-electron oxidant, afforded the two-electron-oxidized product (IP^–)₂Ga­(TEMPO) (<b>4</b>). Reduction of 2IP by 3Na and subsequent reaction with GaCl₃ yielded a 1:1 mixture of (IP^–)₂GaCl and <b>1</b>. Most remarkably, all of these reactions are overall two-electron processes and only the (IP^–)₂GaX and [(IP^2‑)₂Ga]⁻ oxidation states are thermodynamically accessible to us. Analogous aluminum chemistry previously afforded either one-electron or two-electron reactions and mixed-valent states. The thermodynamic accessibility of the mixed-valent states of (IP^2‑)­(IP^–)­E, where E = Al or Ga, can be compared using cyclic voltammetry measurements. These measurements indicated that the mixed-valent state [(IP^2‑)­(IP^–)­Ga]⁺ is not significantly stabilized with respect to disproportionation on the time scale of the electrochemistry experiment. The electrochemically observed differences in thermodynamic stability of the mixed-valent state [(IP^2‑)­(IP^–)­E]⁺ can be rationalized by the observation that the dihedral angle between the ligand planes containing the π-system of IP is roughly 5° larger in all gallium complexes compared with aluminum analogs. Presumably, a larger dihedral angle provides weaker electronic coupling between the π-systems of IP via the E–X σ* orbital. Alternatively, the observed difference may be a result of the “inert pair effect”: a contracted Ga component in the E–X σ* orbital would also afford weaker electronic coupling