Activation of TADF in Photon Upconverting Crystals of Dinuclear Cu(I)-Iodide Complexes by Ligand Engineering.

This work reports that ligand engineering can modulate the triplet harvesting mechanism in iodide-bridged rhombic Cu2I2 complexes. Complex-1, with a smaller Cu-Cu distance, exhibits phosphorescence from 3(M+X)LCT and 3CC states with 66% quantum yield, whereas an increased Cu-Cu distance in complex-2 results in a switch of the emission from phosphorescence to TADF, which occurs via 1/3(M+X)LCT states with 83% quantum yield. The TADF property of complex-2 has been utilized for the fabrication of a pc-LED emitting efficient warm white light. Moreover, the high charge-transfer nature of these complexes leads to the emergence of third-harmonic generation (THG). Interestingly, complex-1 exhibits efficient third-harmonic generation with a χ(3) value of 1.15 × 10-18 m2 V-2 and LIDT value of 14.73 GW/cm2. This work aims to provide a structure-property relationship to achieve effective harvestation of triplet excitons in iodide-bridged rhombic Cu2I2 complexes and their effective utilization in OLED device fabrication and nonlinear photon upconversion processes.

Open shell (4n + 2)π and closed shell 4nπ planar core-modified decaphyrins.

Planar 44π and 46π core-modified decaphyrins with ten thiophene units have been synthesized from short thiophene oligomers. They have been structurally characterized by single crystal X-ray diffraction with further support from spectroscopic analysis and quantum chemical calculations. Our analysis revealed diradicaloid characteristics for 46π species in contrast to the closed shell property of the 44π congener. Further, 44π and 46π undergo reversible two-electron chemical oxidation, as observed by spectro-electrochemical measurements.

Engineering TADF, mechanochromism, and second harmonic up-conversion properties in regioisomeric substitution space.

This research article explores the distinct TADF efficiency of three donor-acceptor based regio-isomers: DPAOCN (ortho-isomer), DPAMCN (meta-isomer), and DPAPCN (para-isomer). DPAPCN exhibits maximum TADF efficiency in both solution and solid-state with an impressive reverse inter-system crossing (RISC) rate of ∼106 s-1; the underlying cause being the minimum singlet-triplet splitting energy or ΔEST and maximum SOC (spin-orbit coupling) between the S1 & T1 states. Apart from TADF, differences in crystal packing of the regio-isomers result in intriguing bulk phase properties. DPAOCN, with its non-centrosymmetric P212121 space group and substantial crystal void volume, exhibits reversible tri-color mechanochromic luminescence behavior, while the meta and para isomers, due to their centrosymmetric packing and diminished crystal void volume, remain inert to mechanical pressure. Expanding the horizon of possibilities, the non-centrosymmetric nature of ortho-isomer further renders it an excellent SHG material, with a χ(2) value of 0.19 pm V-1 at 1220 nm and a laser-induced damage threshold (LIDT) value of 13.27 GW cm-2. Overall, a comprehensive investigation into the regio-isomers has been carried out, encompassing their TADF, SHG, and mechanochromic luminescent properties.

Tetrafluorenofulvalene as a sterically frustrated open-shell alkene.

Electronic and steric effects are known to greatly influence the structure, characteristics and reactivity of organic compounds. A typical π bond is weakened by oxidation (corresponding to the removal of electrons from bonding orbitals), by reduction (through addition of electrons to antibonding orbitals) and by unpairing of the bonding electrons, such as in the triplet state. Here we describe tetrafluorenofulvalene (TFF), a twisted, open-shell alkene for which these general rules do not hold. Through the synthesis, experimental characterization and computational analysis of its charged species spanning seven redox states, the central alkene bond in TFF is shown to become substantially stronger in the tri- and tetraanion, generated by chemical reduction. Furthermore, although its triplet state contains a weaker alkene bond than the singlet, in the quintet state its bond order increases substantially, yielding a flatter structure. This behaviour originates from the doubly bifurcated topology of the underlying spin system and can be rationalized by the balancing effects of benzenoid aromaticity and spin pairing.

Redox Assisted Reversible Aromaticity Transition Between 30π Hückel and 28π Möbius Dication of a Core-Modified Isophlorinoid.

The electronic properties of a hexaphyrin was fine-tuned via core-modification leading to the formation of a Hückel aromatic 30π hexaphyrin which incorporates two pyrrole and four furan rings in the π-conjugated pathway. This Hückel aromatic hexaphyrin modified its conformation upon two-electron ring oxidation either with triflic acid or Meerwein salt [Et3 O]+ [SbCl6 ]- to yield 28π Möbius aromatic dication species. Reversible aromatic transition was established by spectroscopic techniques and further supported by quantum chemical calculations.

Tailoring diradicaloid properties of expanded isophlorinoids with systematic core-modification.

Herein, we describe the synthesis, structural diversity and diradicaloid characteristics of 38π core-modified aromatic expanded isophlorins with eight heterocyclic rings. The diradicaloid character of expanded isophlorinoid macrocycles was engineered by systematic structural modification. Depending on the nature of the link between the heteroatoms, they adopt planar and non-planar conformations. This large structural variation with a significant difference in the extent of aromaticity is correlated with the magnitude of their respective diradical character.

Reversible redox switching between local and global aromaticity for core-modified expanded carbaisophlorinoids.

Two dithienothiophene based 28π antiaromatic macrocycles with benzene and azulene units and their effects on local and global (anti)aromaticity have been described. Experimental and computational studies confirmed the presence of weak paratropic and strong diatropic ring current effects in neutral and dicationic states, respectively.

Emergence of Aggregation Induced Emission (AIE), Room-Temperature Phosphorescence (RTP), and Multistimuli Response from a Single Organic Luminogen by Directed Structural Modification.

Multifunctional organic luminogens exhibiting simultaneous aggregation induced emission (AIE), room-temperature phosphorescence (RTP), and mechanochromism have recently attracted considerable attention owing to their potential applications in optoelectronics and bioimaging. However, a comprehensive correlation among these three distinguished properties is yet to be unveiled, which will help to decipher defined methodologies to design future generation multifunctional organic materials. Herein, we have demonstrated a route to obtain a multifunctional organic luminogen, starting from an ACQphore (TPANDI) by simple structural engineering. We have shown that a slight reduction in length of the planar acceptor moieties can effectively inhibit the undesirable π-π stacking interaction between molecules in the condensed state and thereby cause an ACQ to AIE type transformation from TPANDI to TPANMI and TPAPMI. Both TPANMI and TPAPMI exhibit RTP properties (even in ambient condition) because of the presence of a reasonably low singlet-triplet energy gap (ΔEST). In our study, these two luminogens were found to be mechano-inactive. Interestingly, an insertion of cyano-ethylene group and benzene linker in between the triphenylamine and phthalimide moieties introduced another luminogen TPACNPMI, which can simultaneously exhibit AIE, RTP, and mechanochromic properties.

Three dimensional isophlorinoid tetrapodal molecular cage.

Steric hindrance induced by thiophene molecules in predesigned precursors favors the exclusive formation of a three dimensional (3D) π-conjugated cage and quasi-cage like molecules instead of a porphyrinoid macrocycle. Herein we report the synthesis of a tetrapod 3D fully π-conjugated molecular cage using a simple acid catalysed reaction. The X-Ray crystallography analysis confirmed the tetrapod cage structure and intermediates, which resemble three-fourths or half of the cage structures.

Comparative evaluation of qualitative performance of technical human resource in school eye health program.

PURPOSE: To measure sensitivity and specificity of vision screeners in identifying children with visual impairment and positive signs and symptoms and assess association of effectiveness with individual characteristics of screeners and type of schools screened. METHODS: A total of 1096 children from age 5 to 15 years of age were screened. A total of 396 children were screened from a municipal school, 200 children from a government-aided school, and 500 children from a private school were screened. Four persons with basic 12th standard science qualification willing to be a part of school eye health program were selected who carried out screening in school children after receiving appropriate training. RESULTS: The two vision screeners who had a background of conducting community eye health programs and worked in eye hospital had 100% sensitivity and specificity for presenting visual acuity, squint detection, and blurring. The screening by these screeners was done in private and semi-private schools, respectively. The other two screeners with no such background conducting screening in government schools had 60% and 75% sensitivity in detecting presenting visual acuity, respectively. CONCLUSION: People with a background of organizing community eye health programs and those working in eye hospitals are the best candidates for being trained as new cadre of vision screeners with best results being obtained in private and government-aided schools.

Evaluation of skills transfer in short-term phacoemulsification surgery training program by International Council of Ophthalmology -Ophthalmology Surgical Competency Assessment Rubrics (ICO-OSCAR) and assessment of efficacy of ICO-OSCAR for objective evaluation of skills transfer.

Purpose: To evaluate skills transfer in short-term phacoemulsification surgery training program by International Council of Ophthalmology -Ophthalmology Surgical Competency Assessment Rubrics (ICO-OSCAR) and assessment of efficacy of ICO-OSCAR for objective evaluation of skills transfer. Methods: Prospective analysis of total 1300 phacoemulsification surgeries performed by 52 phacoemulsification trainees divided into three groups based on the previous cataract surgical experience. The pretraining and posttraining average mean scores, independent completion rates (ICR), and complication rates among the groups were calculated and statistically analyzed. Results: Mean age of trainees (N = 52) was found to be 30.98 ± 2.44 years. Mean pretraining scores in the three groups were 42.8 ± 0.2, 46.6 ± 0.2, and 50.1 ± 0.1, respectively, and posttraining mean scores of the groups were 88.4 ± 0.2, 92.3 ± 0.2, and 94.3 ± 0.2, respectively, out of 100. Pretraining independent completion rates (%) were 22.1 ± 2.5, 52.1 ± 2.5, and 62 ± 3.7, respectively, and posttraining independent completion rates (%) were 74.8 ± 3, 79.7 ± 3, and 90.6 ± 3.5, respectively. Learning curves of all groups were noted to be steep. Rate of complications was within acceptable range, overall complication rate being 12.30% (160 out of 1300 cases). OSCAR scores correlate significantly (P = 0.0004) with ICR. Conclusion: Steep learning curve for phacoemulsification can be made easy by the use of standardized rubrics, proper techniques, expert guidance, and adequate surgical volume. The previous SICS experience provides smoother learning curve. ICO-OSCAR is indicator of proficiency and provides constructive feedback and objective evaluation immediately after surgery as well as at the end of training. Short-term (1 Month) training program is an effective, efficient, and safe approach to progressively master phacoemulsification skills for trainees with SICS experience.

A wide-range of redox states of core-modified expanded porphyrinoids.

Core-modified hexaphyrin and octaphyrin display four- and six-electron reversible redox reactions respectively, to alternate between aromatic and anti-aromatic states of a given macrocycle. We have identified and isolated a hexaphyrin in three discrete states with 26π, 28π and 30π electrons that are inter-convertible with each other. Its higher congener, octaphyrin, can exist as four discrete species with 34π, 36π, 38π and 40π electrons. A difference of two-electrons between each stable redox state is reflected by the significant variation in their electronic and structural properties as characterized in both solution and solid states. The observed redox inter-conversions were achieved by a combination of both proton coupled electron-transfer (PCET) and electron-transfer (ET) processes respectively.

Isophlorinoids: The Antiaromatic Congeners of Porphyrinoids.

Ever since the discovery of the porphyrin ring in "pigments of life", such as chlorophyll and hemoglobin, it has become a prime synthetic target for optoelectronic properties and in the design of metal complexes. During one such early expedition on the synthesis of porphyrin, Woodward proposed that condensing pyrrole with an aldehyde under acidic conditions yields the "precursor" porphyrinogen macrocycle. Its four-electron oxidation leads to the "transitory" 20π isophlorin, which undergoes subsequent two-electron oxidation to form the 18π "porphyrin". Due to its fleeting lifetime, it has been a synthetic challenge to stabilize the tetrapyrrolic isophlorin. This macrocycle symbolizes the antiaromatic character of a porphyrin-like macrocycle. In addition, the pyrrole NH also plays a key role in the proton-coupled, two-electron oxidation of isophlorin to the aromatic porphyrin. However, a major aspect of its unstable nature was attributed to its antiaromatic character, which is understood to destabilize the macrocycle upon conjugation. Antiaromaticity in general has not gained significant attention mainly due to the lack of stable 4nπ systems. In this regard, a stable isophlorin and its derivatives provide a glimmering hope to peek into the world of antiaromatic systems. This review will focus on the attempted synthesis of antiaromatic isophlorin ever since its conception. Based on recent synthetic advances, the chemistry of isophlorins can be expected to blossom into expanded derivatives of this antiaromatic macrocycle. Along with the synthetic details, the structural, electronic, and redox properties of isophlorin and its expanded derivatives will be elaborated.

The posterior iris-claw lens outcome study: 6-month follow-up.

PURPOSE: The purpose of this study was to evaluate functional and anatomical outcomes of posterior iris-claw intraocular lens (IOL) implant for correction of aphakia in eyes with inadequate capsular support. MATERIALS AND METHODS: Prospective case series of 108 aphakic eyes with inadequate capsular support which underwent posterior iris-claw IOL with a 6-month follow-up period was conducted. The cases belonged to two clinical settings: elective secondary implantation and those with intraoperative posterior dislocation of cataractous lens or IOL. Main outcome measures were visual acuity, anterior chamber reaction, stability of IOL, endothelial cell count, intraocular pressure (IOP), and cystoid macular edema (CME). RESULTS: The mean best-corrected visual acuity was LogMAR 0.25. None had chronic anterior chamber inflammation. The mean difference in central endothelial counts before surgery and 1 month after surgery was 104.21 cell/mm2 (4.92%). There was no statistically significant difference in central endothelial cell count at 1 and 6 months (P = 0.91) and also in the central macular thickness at preoperative and after 6 months suggestive of CME (P = 0.078). Three eyes had raised IOP which were managed with neodymium-doped yttrium aluminum garnet laser peripheral iridotomy. There were no IOL dislocations or other adverse events in our series. CONCLUSION: Posterior chamber iris-claw lenses are a good option in eyes with inadequate posterior capsular support. Chronic inflammation, poor lens stability, or significant central endothelial cell loss was not observed during the 6-month follow-up period.

Prevalence and determinants of age-related macular degeneration in the 50 years and older population: a hospital based study in Maharashtra, India.

BACKGROUND: We present the magnitude and determinants of age-related macular degeneration (ARMD) among the 50 year and older population that visited our hospital. MATERIALS AND METHODS: This was a cohort of eye patients with ARMD, seen from 2006 to 2009. Optometrist noted the best-corrected vision. Ophthalmologists examined eyes using a slit-lamp bio-microscope. The ARMD was confirmed by fluoresceine angiography and optical coherent tomography. The age, sex, history of smoking, sun exposure, family history of ARMD, diet, body mass index (BMI), hypertension, and diabetes were associated with ARMD. RESULT: Of the 19,140 persons of ≥ 50 years of age-attending eye clinic in our hospital, 302 persons had ARMD in at least one eye. The proportion of overall ARMD was 1.38% (95% CI 1.21--1.55). The proportion of age-related maculopathy (ARM) and late ARMD was 1.14% (95% CI 0.99--1.29) and 0.24% (95% CI 0.21-0.24) respectively. ARM was unilateral and bilateral in 64 (29.2%) and 155 (70.8%) persons respectively. Dry ARMD was found in 47.8%. On regression analysis, old age (OR = 1.05), male (OR = 0.54), and history of smoking (OR = 2.32) were significant risk factors of ARMD. A total of 4.2% of persons with ARMD were blind (vision <3/60). Only 43% of persons with ARMD had J6 grade of the best-corrected near vision. CONCLUSION: ARMD does not seem to be of public health magnitude in the study area. Early stages of ARMD were common among patients. Older age, being male, and history of smoking were significant risk factors for ARMD.

Clinical audit of horizontal strabismus surgery in children in Maharashtra, India.

BACKGROUND: The study aimed to audit the results of horizontal strabismus surgery in the hospital's pediatric ophthalmology department in Maharashtra, India. METHOD: Medical records of strabismus surgeries done over 3 years were collated. Preoperative visual acuity, deviation, refraction, and orthoptic evaluation were noted as well as post-operative residual deviation and patient satisfaction. Post-operative residual deviation < or = 10Delta was considered good outcome, 11-20Delta borderline, and > 20Delta was considered poor outcome. The surgeons were briefed about their results periodically and the cause of poor outcomes discussed. RESULT: Between March 2004 and December 2007, 529 children were operated upon, of whom 461 (87.1%) completed the 6-week follow-up. Average age was 9 years 7 months (range 1-19 years). 260/461 (56.3%) patients had good, 100/461 (21.6%) borderline, and 101/461 (21.9%) had poor outcome. 133/231 (57.6%) cases of esotropia and 127/230 (55.2%) cases of exotropia had a good outcome, while the poor outcome was 50/231 (21.6%) and 51/230 (22.1%), respectively. Bilateral medial rectus recession for esotropia had 25/56 (44.6%) good outcome and 15/56 (26.7%) poor outcome, while recess-resect procedures (R/R) for esotropia had 108/175 (61.7%) good and 35/175 (20%) poor outcome (p = 0.062). Bilateral lateral rectus recession for exotropia had 30/56 (53.6%) good and 12/56 (21.4%) had poor outcome, while for recess-resect procedures for exotropia it was 97/174 (55.7%) good and 39/174 (22.4%) poor outcome (p = 0.97). The result did not significantly change over 3 years. 433/461 (93.9%) expressed satisfaction about the surgery on 6-week follow-up. Large pre-operative deviations and amblyopic eyes accounted for 63/101 (62.3%) cases of poor outcome. Fifty-seven patients recorded an improvement in stereopsis. CONCLUSION: Recess-resect procedures had better outcome as compared to bilateral recess procedures, but it was not statistically significant. Clinical audit helped maintain and improve good outcome over the 3 years.

Safety and efficacy of phacoemulsification compared with manual small-incision cataract surgery by a randomized controlled clinical trial: six-week results.

OBJECTIVE: To compare the efficacy, safety, and refractive errors of astigmatism after cataract surgery by phacoemulsification and manual small-incision cataract surgery techniques. DESIGN: Masked randomized control clinical trial. PARTICIPANTS: Four hundred eyes of 400 patients, 1:1 randomization with half in each arm of the trial. METHODS: A total of 400 eyes was assigned randomly to either phacoemulsification or small-incision groups after informed consent and were operated on by 4 surgeons. They were masked to the technique of surgery before, during, and after cataract surgery and followed up to 1 year after surgery. The intraoperative and postoperative complications, uncorrected and best-corrected visual acuity, and astigmatism were recorded at 1 and 6 weeks postoperatively. MAIN OUTCOME MEASURES: The proportion of patients achieving visual acuity better than or equal to 6/18 with and without spectacles after cataract surgery in the operated eye up to 6 weeks, postoperative astigmatism, and complications during and after surgery. RESULTS: This article reports clinical outcomes up to 6 weeks. Three hundred eighty-three of 400 (95.75%) patients completed the 1-week follow-up, and 372 of 400 (93%) patients completed the 6-week follow-up. One hundred thirty-one of 192 (68.2%) patients in the phacoemulsification group and 117 of 191 (61.25%) patients in the small-incision group had uncorrected visual acuity better than or equal to 6/18 at 1 week (P = 0.153). One hundred fifty of 185 (81.08%) patients of the phacoemulsification group and 133 of 187 (71.1%) patients of the small-incision group (P = 0.038) were better than or equal to 6/18 at the 6-week follow-up for presenting visual activity. Visual acuity improved to > or = 6/18 with best correction in 182 of 185 patients (98.4%) and 184 of 187 (98.4%) patients (P = 0.549), respectively. Poor outcome (postoperative visual acuity < 6/60) was noted in 1 of 185 (0.5%) in the phacoemulsification group and none in the small-incision group. The mode of astigmatism was 0.5 diopters (D) for the phacoemulsification group and 1.5 D for the small-incision group, and the average astigmatism was 1.1 D and 1.2 D, respectively. There was an intra-surgeon variation in astigmatism. The phacoemulsification group had 7 posterior capsular rents compared with 12 in the small-incision group, but the phacoemulsification group had more corneal edema on the first postoperative day. CONCLUSIONS: Both the phacoemulsification and the small-incision techniques are safe and effective for visual rehabilitation of cataract patients, although phacoemulsification gives better uncorrected visual acuity in a larger proportion of patients at 6 weeks.

Automation and robotics for genetic analysis.

This guide to laboratory robotics covers a wide variety of methods amenable to automation including mapping, genotyping, barcoding and data handling, template preparation, reaction setup, colony and plaque picking, and more.