Heteroatoms In Ring Research Articles

The impact of hetero-aromatic rings on optoelectronic and charge transport properties of fused polycyclic compounds

The structural, optoelectronic, and charge-transport properties of linearly fused polycyclic hydrocarbon molecules with heteroatoms (NH, O, S, and Se) in five-membered rings have been investigated using the DFT approach. The hybrid functional B3LYP in combination with the 6–311 + G (d,p) basis set is utilized in the Gaussian 16 W software package for all the calculations. The absorption and emission energies are investigated by using time-dependent density functional theory (TD-DFT) at the same level of theory. To investigate the stability of each molecule concerning its aromaticity, nucleus-independent chemical shift (NICS) values are computed. Electron affinity (EA), hole extraction potential (HEP), ionization potential (IP), and electron extraction potential (EEP) are also reported. The simulated hole (λ h) and electron (λ e) reorganization energies for the majority of the molecules are lower than the characteristics hole and electron-transporting materials. The reported fused polycyclic compounds may have potential applications in optoelectronic devices.

Selective hydroconversion of ethanolyzed soluble portion from the ethanolysis of Hanglaiwan long flame coal extraction residue over highly active Ni/SAPO-34 catalyst

The ethanolyzed soluble portion (SPE) prepared from the ethanolysis of Hanglaiwan long flame coal (HLFC) extraction residue was converted to catalytically hydroconverted SPE (CHSPE) by the catalytic hydroconversion (CHC) over Ni10 %/SAPO-34 at 200 °C under an initial hydrogen pressure of 5 MPa for 24 h. The possible mechanisms for the origin and synergic effect of active hydrogen had been speculated according to the reactions of HLFC-related model compounds. H2 can be activated by Ni10 %/SAPO-34 to produce H···H, H+, and H-, the synergic effect of which leads to cleaving >C-O- bonds. After the CHC, arenes and heteroatom-containing aromatic compounds in SPE are converted to cyclanes, indicating that aromatic ring hydrogenation and heteroatom removal occur simultaneously during the CHC of SPE. The relative abundance (RA) of CH-containing species in CHSPE is larger than that in SPE, while the RAs of oxygen- and nitrogen-containing species in CHSPE are smaller than those in SPE. In addition, Ni10 %/SAPO-34 has excellent cyclability for the CHC of SPE, and the relative content of cyclanes decreases only by 17.4 % after five recycles. Undoubtedly, this investigation provides an effective strategy for directional upgrading of derived soluble portion from low metamorphic coals.

Molecular-atomic scale insights into polymer-asphalt interactions induced by the oxidation of reactive oxygen species via computational simulation and multifield microscopy characterization

The objective of this study is to investigate the intermolecular interactions between polymers and asphalt components due to the oxidation of reactive oxygen species (ROS). Quantum chemistry (QC) and molecular dynamics (MD) were employed to simulate the molecular properties and intermolecular interactions between SBS and asphalt components during ROS aging. Multifield optical microscopy was utilized to analyze the microstructural characteristics and validate intermolecular interactions of SBS and asphalt components during ROS aging. The results show that asphaltenes have the most uneven electrostatic potential (ESP) distribution, followed by resins and aromatics, while saturates exhibit the most uniform ESP distribution. ROS aging leads to a more uneven ESP distribution and a higher polarity for HiMA molecules, especially for asphaltenes and resins with increased formation of polar functional groups. SBS and saturates exhibit small energy gaps and electronic softness, indicating good resistance to ROS oxidation, whereas asphaltenes and resins are prone to free radical oxidation reactions with ROS. The potential ROS oxidation site of asphaltenes and resins are mainly distributed in benzene ring regions and heteroatoms, while that of SBS are primarily located at the polybutadiene chains. The interactions between SBS and asphalt components are primarily driven by van der Waals forces. However, the hydrogen bonding appears after ROS aging, enhancing the intermolecular interactions. The interaction energies of SBS-asphaltenes and SBS-resins are significantly enhanced, and the intermolecular distances are shortened as ROS aging progresses. Multifield microscopy observation reveals that the development of bee structures in polymer regions is significantly faster than that in asphalt regions, indicating a significantly enhanced adsorption of asphaltenes by polymers after ROS aging. This is attributed to the uneven charge distribution, increased polarity, and enhanced reactivity of asphaltenes and SBS due to ROS aging. This study contributes to a molecular-atomic-level understanding of the intermolecular interactions between polymers and asphalt components during ROS aging.

Chemical and electrochemical nanofabrication of polyaminothiazole/graphene oxide composites

Poly(2-aminothiazole) is a little-studied conducting polymer with sulfur and nitrogen heteroatoms in the aromatic ring, which reveals prospects for application in various fields. We studied the conditions of chemical synthesis of poly(2-aminothiazole) and its composite with graphene oxide in an aqueous solution, as well as electrochemical deposition on electrode surfaces – Pt and SnO2. The structure of the polymer was investigated by SEM and FT-IR spectroscopy. A quantum-chemical calculation using the semi-empirical PM7 method was carried out. The electrochemical activity of polymer films was examined. Increasing effective parameters of charge transport for poly(2-aminothiazole)/graphene oxide films were detected.

Oxaphosphiranes: isolable phosphorus-containing epoxide rings.

Combining different heteroatoms in an epoxide-type ring having Lewis basic and acidic characteristics is challenging as it creates an increasing number of polar bonds and high ring strain energy. The first examples of isolable oxaphosphiranes, i.e., epoxide rings with a phosphorus atom, have been synthesized using a facile and effective protocol starting from [pentacarbonyl{dichloro(trityl)phosphane}molybdenum(0)] (trityl = CPh3), tert-butyllithium and commercially available fluorinated benzaldehydes. Reactions with various acids and bases will be described. Theoretical results unveil a singlet carbene-like FMO situation at phosphorus in oxaphosphirane, which is used to explain reaction mechanisms.

B-P Coupling: Metal Stabilized Phosphinoborate Complexes.

In an effort to establish B-P coupling reactions without the use of phosphine-borane dehydrocoupling agent, we have developed a new synthetic methodology employing group 8 metal σ-borate complex [{κ3 -H,S,S'-BH2 L2 }Ru{κ3 -H,H,S-BH3 L}] (L=NC5 H4 S), 1. Treatment of 1 with chlorodiphenyl phosphine (PPh2 Cl) yielded 1,5-P,S chelated Ru-dihydridoborate species [PPh2 H{κ3 -H,H,S-BH(OH)L}Ru{κ2 -P,S-(Ph2 P)BH2 L}], 2. The insertion of phosphine moiety (PPh2 ) by the cleavage of 3c-2e σ(Ru… H-B) bonding interaction led to the formation of B-P bond. The κ2 -P,S chelated six-membered ring adopted a boat conformation in complex 2. The heterocycle is made of all different atoms, which is one of the rarest examples of heteroatomic ring systems. Theoretical outcomes demonstrated the electronic insight of B-P coupling and stabilization through transition metal. In order to explore an alternate route of B-P bond formation, we have further explored the reaction of 1 and Ru-bis(dihydridoborate) complex, 5 with secondary phosphine oxide (SPO). Although, thermolysis of 1 with diphenylphosphine oxide yielded analogous σ-borate complex 3, the similar reaction of 5 at room temperature led to the formation of novel phosphinous(III) acid incorporated Ru(σ-borate)(dihydridoborate) complex, 6. In a similar fashion, the reaction of 5 with phosphite ligand generated Ru(σ-borate)(dihydridoborate) complex, 7, which is analogous to 6.

One-Pot Synthesis, E-/Z-Equilibrium in Solution of 3-Hetarylaminomethylidenefuran-2(3H)-ones and the Way to Selective Synthesis of the E-Enamines.

We describe a method to synthesize a new class of hetarylaminomethylidene derivatives of furan-2(3H)-ones. The method uses 5-(4-chlorophenyl)furan-2(3H)-one, triethyl orthoformate, and heterocyclic amines with different ring sizes and heteroatoms under refluxing in absolute isopropyl alcohol. The obtained enamines exist in an equilibrium of E- and Z-isomers, whose configurations relative to the double exocyclic C=C bond were confirmed with a set of NMR spectroscopy data. The E-/Z-equilibrium of the synthesized compounds is affected by the configuration of the intermediate, the volume of its substituents, the site of enolate attack, the presence of intramolecular interactions of amino components, the time of the transformation, the order of mixing of the initial reagents, and the use of polar solvents in the NMR experiment. The advantages of the method are that the reaction time is short, the product yield is high, and product purification is easy.

Novel Synthetic ‘Triangle Ester’ Lubricants: Useful Correlations for Wetting and Tribological Phenomena Over Common Engineering Substrates

The surface free energy (SFE) of engineering substrates and the surface tension (ST) of lubricants are known to influence wetting behavior at the interface of the mating mechanical components. The influence of cyclic moieties and heteroatoms in modulating wetting behavior and consequent tribological properties like friction and wear is less well elucidated. Continuing our exploration of “triangle esters” distinguished by the introduction of three-membered heteroatom rings in otherwise commonly used lubricant structures, we demonstrate that friction and wear properties for each ester over a set four different metallic engineering substrates—aluminum, brass, phosphor bronze, and stainless steel—under low load conditions can be effectively correlated with surface properties for the coefficient of friction, and with both surface properties and substrate hardness for wear parameters. The experimentally determined regression equations are used to predict these properties for a fifth substrate, gun metal. The difference in polarity fraction between the substrate and the lubricant is found to have a surprisingly significant influence on wear properties.

Tracing the composition and structure evolution of oxygen-enriched asphaltenes during the hydrotreating of middle-low temperature coal tar

Inefficient conversion of structure-complicated and oxygen-enriched asphaltenes is found as the major challenge facing coal tar in achieving high value-added utilization. Hydrogenation technology is the primary way to achieve the impurity removal and lightweight of coal tar asphaltenes (CTAS). In this study, the evolution laws of functional groups and structural parameters at different reaction times, and pyrolysis behavior at different temperatures of coal tar asphaltenes (CTAS) during the hydrotreating (HDT) process were investigated using the methods of FT-IR, XPS, 1H NMR, 13C NMR and Py-GC/MS. It was found that the increase of the reaction time significantly affected CTAS hydrodeoxygenation (HDO), and most of nitrogen-containing compounds (NCs) and sulfur-containing compounds (SCs) could be removed in a shorter reaction time. However, the increase of the reaction time has a limited effect on the removal of NCs and SCs embedded in polycyclic aromatic compounds. The average alkyl chain length (L) decreased with the increase of the reaction time, and the degree of branching for alkyl side chains (B) increased after HDT. The aromatic ring substitution degree (σ) and alkyl substituents number (n) of CTAS increased after HDT. The OH-OH and OH-ether O were found as the major hydrogen bonds in asphaltene feed (Asp-feed) and asphaltene product (Asp-product), followed by OH-π and cyclic OH. With the increase of reaction time, the molar fraction of the OH-ether O hydrogen bonds increased, while OH-π hydrogen bonds decreased. C-O group was found as the critical oxygen-containing functional group in Asp-feed and Asp-product, primarily existing in the form of aromatic ether groups and C-O of phenols. With the increase of reaction time, the molar fraction of aromatic ether groups in CTAS increased significantly, while that of the C-O of phenols decreased. The pyrolysis fragments of Asp-feed and Asp-product were largely 1–3 ring aromatic hydrocarbons or heteroatoms compounds. Heteroatoms compounds primarily consisted of phenols and furans, whose alkyl side chains were short and few, mainly existing in the form of multiple methyl groups. The Asp-product produced smaller aromatic ring fragments, more aromatic hydrocarbons and less phenolic and non-phenolic oxygenated compounds than Asp-feed at the same pyrolysis temperatures

Crystal structure and antidiabetic activity of 2-aminospiropyrazolinium tosylates and the product of O-tosylation of β-(benzimidazol-1-yl)propioamidoxime.

2-Amino-1,5-diazaspiro[4.5]dec-1-en-5-ium salts possess bioactivity tuned by the nature of the heteroatoms in the six-membered ring and the counter-ion. The molecular environment of these cations in solids provides an opportunity to establish the conformations and hydrogen-bonding patterns typical for this family. β-Aminopropioamidoxime tosylation products [2-amino-1,5-diazaspiro[4.5]dec-1-en-5-ium tosylates and the product of the O-tosylation of β-(benzimidazol-1-yl)propioamidoxime, namely, 2-amino-1,5-diazaspiro[4.5]dec-1-en-5-ium tosylate, C8H16N3+·C7H7O3S- (6), 2-amino-8-oxa-1,5-diazaspiro[4.5]dec-1-en-5-ium tosylate, C7H14N3O+·C7H7O3S- (7), the monohydrate of 7, C7H14N3O+·C7H7O3S-·H2O (7a), 2-amino-8-thia-1,5-diazaspiro[4.5]dec-1-en-5-ium tosylate, C7H14N3S+·C7H7O3S- (8), 2-amino-8-phenyl-1,5,8-triazaspiro[4.5]dec-1-en-5-ium tosylate, C13H19N4+·C7H7O3S- (9), and 3-(1H-benzimidazol-1-yl)-N'-(tosyloxy)propanimidamide, C17H18N4O3S (10)] were investigated using X-ray diffraction to study peculiarities of their molecular geometry and intermolecular interactions. In vitro antitubercular and antidiabetic screening of the β-aminopropioamidoxime tosylation products was also carried out. It was revealed that this series of compounds does not have activity against drug-sensitive and multidrug-resistant M. tuberculosis strains, and exhibits high and moderate antidiabetic α-amylase and α-glucosidase activity. Using the hydrogen-bond propensity tool, we found that the inclination of counter-ions and atoms to act as acceptors of hydrogen bonds for the amino group decreases passing from tosylate O atoms to water molecules and the N atoms of five-membered rings. This fact is probably the reason for the formation in the solids of hydrogen-bonded tetramers consisting of two anions and two cations, and the rare occurrence of 2-aminospiropyrazolinium salt hydrates.

Multifunctional Oxazolone Derivative as an Optical Amplifier, Generator, and Modulator.

An optical control of many working optoelectronic systems (real-time sensors, optical modulators, light amplifiers, or phase retarders) giving efficient optical gain or remote signal modulation is currently included as scientifically and industrially interesting. In here, an oxazolone derivative as the multifunctional organic system is given in this contribution. The molecule possesses a stilbene group and an oxazolone heteroatomic ring, which implies effective refractive index manipulation and multimode lasing action, respectively. The light modulation is repeatable and stable, also in the hundreds of Hz regime. On the other hand, the amplified optical signal can be easily generated by an external optical pumping source. Thus, signal control is fully available, as is read-in and read-out of the information in real time. Furthermore, this third-order, nonlinear, optical phenomenon using a third harmonic generation technique was also observed. We discovered that only by changing the energy and time regime of the supplied optical signal is the optical or nonlinear optical response observed. Two heteroenergetic molecular states (trans (E) and cis (Z)) can efficiently operate in modern multifunctional optoelectronic systems, which can provide and generate an optical signal. Such functionalities are commonly used in all-optical photonic switchers and logic gates and can be utilized in optical-core networks and computers.

Sulfur Functionalization via Epoxide Ring Opening on a Reduced Graphene Oxide Surface to Form Metal (II) Organo-bis-[1,2]-oxathiin.

The epoxide ring-opening reaction in graphene oxide (GO) by nucleophiles is a very fascinating and advanced methodology to develop novel functional material. Herewith, we report an advanced strategy for opening the epoxide ring on the rGO surface via easily an available nucleophile (Na2S), which is further functionalized with O atom to obtain four-membered rings (FMRs). The Cd coordination with the S atom puts extra stress on the FMR leading to the C-C bond cleavage of the four-membered heteroatomic rings on the rGO surface. This strategic approach leads to the fabrication of an innovative metal (II) organo-bis-[1,2]-oxathiin (MOBOT) chemical moiety (M = Cd, Zn). The MOBOT compound further shows enhanced H2 generation activity and hence is promising as a potential photocatalyst for solar hydrogen generation. This compound might also be a potential candidate for optoelectronic applications.

Effects of azole rings with different chalcogen atoms on ESIPT behavior for benzochalcogenazolyl-substituted hydroxyfluorenes

ESIPT behavior has attracted a lot of eyes of researchers in recent years because of its unique optical properties. Due to its large Stokes shift and double emission fluorescence, white light can be generated in the fluorophore based on the excited state intramolecular proton transfer (ESIPT) principle. The excited state proton transfer behavior of hydroxylated benzoxazole (BO-OH), benzothiazole (BS-OH) and benzoselenazole (BSe-OH) have been investigated in heptane, chloroform and DMF solvents. By comparing the infrared vibration spectra and the variation of bond parameters from the S0 to S1 states, and analyzing the frontier molecular orbitals, the influence of hydrogen bond dynamics, the solvent polarity, charge redistribution and the effects of different proton acceptors on proton transfer were observed. The only structural difference among the three substituted hydroxyfluorenes is the heteroatom in the azole ring (oxygen, sulfur and selenium, respectively). We have scanned the potential energy curve of the ESIPT process, and compared the potential barrier, it is found that the heavier chalcogen atoms are more favorable for proton transfer. At the same time, the potential application of changing heteroatoms in the azole ring by walking down the chalcogenic group in crystal luminescence color regulation is also discussed.

Nitrogen-Doped Carbons Derived from Imidazole-Based Cross-Linked Porous Organic Polymers.

Nitrogen-doped and heteroatom multi-doped carbon materials are considered excellent metal-free catalysts, superior catalyst supports for transition metal particles and single metal atoms (single-atom catalysts), as well as efficient sorbents for gas- and liquid-phase substances. Acid-catalyzed sol–gel polycondensation of hydroxybenzenes with heterocyclic aldehydes yields cross-linked thermosetting resins in the form of porous organic polymers (i.e., organic gels). Depending on the utilized hydroxybenzene (e.g., phenol, resorcinol, phloroglucinol, etc.) and heterocyclic aldehyde variety of heteroatom-doped organic polymers can be produced. Upon pyrolysis, highly porous and heteroatom-doped carbons are obtained. Herein, polycondensation of phloroglucinol with imidazole-2-carboxaldehyde (and other, similar heterocyclic aldehydes with two heteroatoms in the aromatic ring) is utilized to obtain porous, N-doped organic and carbon gels with N-content of up to 16.5 and 12 wt.%, respectively. Utilization of a heterocyclic aldehyde with two different heteroatoms yields dually-doped carbon materials. Upon pyrolysis, the porous polymers yield ultramicroporous N-doped and N,S co-doped carbons with specific surface areas of up to 800 m2g−1. The influence of the initial composition of reactants and the pyrolysis temperature on the structure and chemical composition of the final doped organic and carbon materials is studied in detail.

Effect of the donor units on the properties of fluorinated acceptor based systems

A new series of monomers in the donor-acceptor-donor array, namely 5-fluoro-4,7-di(furan-2-yl)benzo[c][1,2,5]thiadiazole (F2BT-F), and 5-fluoro-4,7-di(selenophen-2-yl)benzo[c][1,2,5] thiadiazole (S2BT-F), bearing 5-fluorobenzo[c][1,2,5]-thiadiazole as the acceptor moiety and furan and selenophene as the electron donating groups was synthesized and polymerized electrochemically. To compare heteroatom effect, thiophene analogue of newly synthesized F2BT-F and S2BT-F namely, (5-fluoro-4,7-di(thiophen-2-yl)benzo[c][1,2,5] thiadiazole (T2BT-F)) and its corresponding polymer were also synthesized. Effect of donor units on the electrochemical and optical properties of fluorinated acceptor based systems was investigated in terms of the effect of different sized heteroatoms in five-membered rings on the dihedral angle and planarity. Theoretical calculations also suggested a deviation from planarity upon fluorination. Moreover, electrochemically obtained polymers possess low bandgap values (1.62 eV–1.68 eV for PF2BT-F and PS2BT-F, respectively) and exhibited electrochromic properties with relatively low switching times.

The Advance of Anti-Cancer Flexible Heteroarotinoids

Retinoids have clinically proven anti-cancer activities. However, the toxicity of retinoids hinders their application in vivo. Heteroatom substitution on the ring structure in retinoids has resulted in a new class of chemical called heteroarotinoids, which have dramatically lower toxicity. Further modifications have led to flexible heteroarotinoids (Flex-Het). Flex-Hets contain a flexible linker between the heteroatom ring and aryl ring. Among all Flex-Hets, SHetA2, which contains a sulfur heteroatom and a thiourea linker, has been the most promising compound with the highest anti-cancer activity until recently. It has been shown effective against all of over 60 cancer cell lines in the US National Cancer Institute. It is a candidate for clinical trials for the treatment of ovarian cancer. SHetA2 induces both intrinsic (mitochondrial mediated) and extrinsic (death receptor mediated) apoptosis pathways in cancer cells with low toxicity and differential activity against malignant versus normal cells. Heat shock protein HSPA9 (mortalin), which interacts with the tumor protein p53, has been found to be the receptor protein of SHetA2. Binding of SHetA2 to mortalin interrupts p53-mortalin interaction, releasing protein p53 to nucleus where it initiates apoptosis. In this article, the chemistry evolution, anti-cancer activity, biological mechanism, and development of better analogues of Flex-Hets are reviewed.

Polyanionic Frameworks in the Lithium Phosphidogermanates Li2GeP2 and LiGe3P3 – Synthesis, Structure, and Lithium Ion Mobility

Recently fast lithium ion conductors were discovered in compounds containing tetrahedral SiP48– and GeP48– units. In the context of material development for all solid state batteries the ternary Li/Ge/P phase system has been further investigated and two new lithium phosphidogermanates were discovered on the lithium poor side of the ternary composition diagram. Li2GeP2 crystallizes in space group I41/acd with unit cell parameters of a = 12.3069(1) Å and c = 19.0306(4) Å, consists of a framework of Ge4P10 supratetrahedra, and exhibits an ionic conductivity of 1.5(3)×10–7 S·cm–1 at 27 °C. LiGe3P3 crystallizes in Pbam with a = 9.8459(5) Å, b = 15.7489(7) Å, and c = 3.5995(2) Å. In LiGe3P3 Ge and P atoms form a two dimensional polyanion. The slabs consist of five‐ and six‐membered heteroatomic rings comprising GeP4 and Ge(P3Ge) tetrahedra including homoatomic Ge–Ge bonds. A semiconducting behavior with an electronic conductivity of ∼10–4 S·cm–1 and a remarkable stability vs. air and moisture is observed.

Reactions of concerted decomposition of cyclic molecules, as studied by the quantum chemistry methods and parabolic model

Reactions of concerted decomposition of cyclic molecules (Diels—Alder retro-reactions) were studied using quantum chemical modeling and the method of intersecting parabolas (M3IP model). According to results of quantum chemical calculations and topological analysis of transition states (TSs) of five concerted decomposition reactions of cyclic molecules, all TSs represent six-membered rings in which the bonds being cleaved are weak covalent ones. The presence of ring heteroatoms (N, O, or S) has a strong impact on the TS geometry and on the energy characteristics of the reactions. The M3IP model was used to process the experimental results to develop an algorithm for calculating the activation energies (E) of the reactions in question and the classical potential barriers to thermally neutral reaction (Ee0). Factors influencing the energies E were determined and assessed. These include the enthalpy of reaction, substituents, ring heteroatoms, the force constants of bonds, and the bond dissociation energies. A comparison of the activation energies E and the enthalpies of reaction ΔH obtained from the M3IP and density functional B3LYP/6-311++G** calculations revealed good agreement between them.

Fine-mapping of the substrate specificity of human steroid 21-hydroxylase (CYP21A2)

Cytochrome P450 enzymes (CYPs) are capable of catalyzing regio- and stereo-specific oxy functionalization reactions, which otherwise are major challenges in organic chemistry. In order to make the best possible use of these biocatalysts it is imperative to understand their specificities. Human CYP21A2 (steroid 21-hydroxylase) acts on the side-chain attached to C-17 in ring D of a steroid substrate, but the configuration of ring A also plays a prominent role in substrate cognition. Here, we comprehensively investigated this relationship using sixteen 17,17-dimethyl-18-nor-13-ene steroids with different arrangements of hydroxy-, oxo-, fluoro- and chloro-groups and in the presence or absence of double bonds (Δ1 and/or Δ4) and heteroatoms in ring A. The results show that presence of a 3-oxo group is a strict requirement for a CYP21A2 substrate, while the other configurations tested were all tolerated. This was also confirmed by control experiments using endogenous steroids. While progesterone and 17-hydroxyprogesterone were hydroxylated at C-21, (17-hydroxy-) pregnenolone did not react. Molecular docking experiments indicate that the interaction of the carbonyl group at C-3 to the side-chain Arg234 of the enzyme is indispensable.

The Influence of Structural Variations on the Heteroacenes Containing Dihydropyrrolo[3,2‐b]pyrrole Core on Their OFET Performances

AbstractHeteroacenes containing a dihydropyrrolo[3,2‐b]pyrrole core such as 5,10‐dihydroindolo[3,2‐b]indole (DBPP) and dinaphtho [2,3‐b:2’,3’‐f]pyrrolo[3,2‐b]pyrrole(DNPP) are potential p‐type semiconductors for organic field‐effect transistors (OFETs) owing to their electron‐rich and easy‐to‐modify core structure. Here we report that how the structural variations such as ring fusion pattern, heteroatom introduction and chlorination influence the crystallinity, orientation and morphology of this type of heteroacenes hence their OFET performance. It is revealed that angular fused C8‐iso‐DNPP has a higher HOMO energy level with matches better with the work‐function of Au and shows better crystallinity and more uniformed morphology compared to the linearly fused isomer C8‐DNPP. Thus it exhibits very similar hole mobility to C8‐DNPP but much smaller threshold voltages. On the other hand, the introduction of extra N atoms into DNPP affords an analogue DQPP and greatly alters the orientation of the crystalline film from “edge‐on” to “face‐on”, which results in a two‐order decrease of the hole mobility. Our result also shows that heavily chlorinated DBPP (TClDBPP) leads to the completely loss of the hole transport capability due to the large π‐π distance imposed by the large chlorine atoms.